Illegal Immigration: Border-Crossing Deaths Have Doubled Since
1995; Border Patrol's Efforts to Prevent Deaths Have Not Been
Fully Evaluated. (15-AUG-06, GAO-06-770).
Reports in recent years have indicated that increasing numbers of
migrants attempting to enter the United States illegally die
while crossing the southwest border. The Border Patrol
implemented the Border Safety Initiative (BSI) in 1998 with the
intention of reducing injuries and preventing deaths among
migrants that attempt to cross the border illegally. GAO
assessed: (1) Trends in the numbers, locations, causes, and
characteristics of border-crossing deaths. (2) Differences among
the Border Patrol sectors in implementing the BSI methodology.
(3) The extent to which existing data allow for an evaluation of
the effectiveness of the BSI and other efforts to prevent
border-crossing deaths.
-------------------------Indexing Terms-------------------------
REPORTNUM: GAO-06-770
ACCNO: A58720
TITLE: Illegal Immigration: Border-Crossing Deaths Have Doubled
Since 1995; Border Patrol's Efforts to Prevent Deaths Have Not
Been Fully Evaluated.
DATE: 08/15/2006
SUBJECT: Border control
Border security
Data collection
Evaluation methods
Illegal aliens
Immigration
Immigration and naturalization law
Mortality
Statistical methods
INS Border Safety Initiative
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GAO-06-770
United States Government Accountability Office
GAO
Majority Leader, U.S. Senate
August 2006
ILLEGAL IMMIGRATION
Border-Crossing Deaths Have Doubled Since 1995; Border Patrol's Efforts to
Prevent Deaths Have Not Been Fully Evaluated
GAO-06-770
ILLEGAL IMMIGRATION
Border-Crossing Deaths Have Doubled Since 1995; Border Patrol's Efforts to
Prevent Deaths Have Not Been Fully Evaluated
What GAO Found
GAO's analysis of data from the BSI, the National Center for Health
Statistics (NCHS), and studies of state vital registries shows consistent
trends in the numbers, locations, causes, and characteristics of migrant
border-crossing deaths that occurred along the southwest border between
1985 and 2005. Since 1995, the number of border-crossing deaths increased
and by 2005 had more than doubled. This increase in deaths occurred
despite the fact that, according to published estimates, there was not a
corresponding increase in the number of illegal entries. Further, GAO's
analysis also shows that more than three-fourths of the doubling in deaths
along the southwest border since 1995 can be attributed to increases in
deaths occurring in the Arizona desert.
Differences among the BSI sector coordinators in collecting and recording
data on border-crossing deaths may have resulted in the BSI data
understating the number of deaths in some regions. Despite these
differences, our analysis of the BSI data shows trends that are consistent
with trends identified in the NCHS and state vital registry data. However,
the Border Patrol needs to continue to improve its methods for collecting
data in order to accurately record deaths as changes occur in the
locations where migrants attempt to cross the border-and consequently
where migrants die. Improved data collection would allow the Border Patrol
to continue to use the data for making accurate planning and resource
allocation decisions.
Comprehensive evaluations of the BSI and other efforts by the Border
Patrol to prevent border-crossing deaths are challenged by data and
measurement limitations. However, the Border Patrol has not addressed
these limitations to sufficiently support its assertions about the
effectiveness of some of its efforts to reduce border-crossing deaths. For
instance, it has not used multivariate statistical methods to control for
the influences of measurable variables that could affect deaths, such as
changes in the number of migrants attempting to cross the border.
Migrant Border-Crossing Deaths, 1985 through 2005
Number of deaths
100
0
1985 1990 1995 2000 2005
Year of death
NCHS data BSI data State vital registry data
United States Government Accountability Office
Contents
Letter Results in Brief BackgroundBSI and NCHS Data Show That, 1 3
Since the Late 1990s, Increases in Deaths along the 6 14
Southwest Border Were Accounted for by Increases in 25
Deaths in the Tucson Sector The Border Patrol's Approach 28
to Tracking and Recording Deaths Has Not Been 31
Implemented Consistently across Sectors Evaluating the 32
Effectiveness of the BSI and Other Border Patrol Efforts
to Reduce Border-Crossing Deaths Presents Measurement
Challenges Conclusions Recommendations for Executive
Action
Appendix I Objectives, Scope, and Methodology Methods to Determine 34
the Reliability of Sources of Data on Border-Crossing 35
Deaths Methods Used to Identify Trends in Federal Data 40
on the Numbers, Locations, Causes, and Characteristics 46
of Border-Crossing Deaths Methods to Determine the
Extent to Which the BSI Can Be Evaluated
Appendix II Deaths by Sector 49
Appendix III Causes of Death 58
Appendix IV Causes of Death for U.S. Residents and Migrants within 60
the BSI Target Zone
Appendix V Comments from the Department of Homeland Security 61
Appendix VI GAO Contacts and Staff Acknowledgments
Tables
Table 1: Number of Migrant Border-Crossing Deaths Occurring in
Pima County, Arizona, as Reported by Various Sources,
2002 through 2005 14 Table 2: Estimated Undocumented Entries,
Apprehensions, and
Deaths 42 Table 3: The Residual Method for Estimating the Number of
Unauthorized Migrants 43
Figures
Figure 1: Border Patrol Sectors and the BSI Target Zone along the
United States-Mexico Border 8
Figure 2: Migrant Border-Crossing Deaths in the BSI Target
Zone,
1985 through 2005 16
Figure 3: Percentage of All Migrant Border-Crossing Deaths in
the
BSI Target Zone Occurring within the Tucson Sector,
1985 through 2005 17
Figure 4: Percentage of All Migrant Border-Crossing Deaths in
the
BSI Target Zone Due to Heat Exposure, 1985 through 2005 19
Figure 5: Migrant Border-Crossing Deaths, by Cause of Death,
NCHS Data, 1990 through 2003 20
Figure 6: Migrant Border-Crossing Deaths and Apprehensions in
the BSI Target Zone Occurring within the Tucson Sector,
Fiscal Years 1998 through 2005 22
Figure 7: Migrant Border-Crossing Deaths and Apprehensions in
the BSI Target Zone Occurring within All Sectors except
Tucson, Fiscal Years 1998 through 2005 23
Figure 8: Migrant Border-Crossing Deaths in the BSI Target Zone
Occurring within the San Diego Sector, 1985 through 2005 49
Figure 9: Migrant Border-Crossing Deaths in the BSI Target Zone
Occurring within the El Centro Sector, 1985 through 2005 50
Figure 10: Migrant Border-Crossing Deaths in the BSI Target
Zone
Occurring within the Yuma Sector, 1985 through 2005 51
Figure 11: Migrant Border-Crossing Deaths in the BSI Target
Zone
Occurring within the Tucson Sector, 1985 through 2005 52
Figure 12: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the El Paso Sector, 1985 through 2005 53 Figure 13: Migrant
Border-Crossing Deaths in the BSI Target Zone Occurring within the Marfa
Sector, 1985 through 2005 54 Figure 14: Migrant Border-Crossing Deaths in
the BSI Target Zone Occurring within the Del Rio Sector, 1985 through 2005
55 Figure 15: Migrant Border-Crossing Deaths in the BSI Target Zone
Occurring within the Laredo Sector, 1985 through 2005 56
Figure 16: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Rio Grande Valley Sector, 1985 through 2005 57
Figure 17: Migrant Border-Crossing Deaths, by Cause of Death, CIR
Findings, 1985 through 1998 58 Figure 18: Migrant Border-Crossing Deaths,
by Cause of Death, BSI Data, 1998 through 2005 59
Figure 19: Percentage Distribution of Deaths among U.S. Residents and
Migrant Border-Crossers, by Cause of Death, All Years Combined, 1990
through 2003 60
Abbreviations
ABCI Arizona Border Control Initiative
BORSTAR Border Patrol Search, Trauma, and Rescue
BSI Border Safety Initiative
BSITS Border Safety Initiative Tracking System
CDC Centers for Disease Control and Prevention
CIR Center for Immigration Research, University of Houston
CPS Current Population Survey
ICD International Classification of Diseases
INS Immigration and Naturalization Service
IRP Interior Repatriation Program
LRP Lateral Repatriation Program
NCHS National Center for Health Statistics
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separately.
United States Government Accountability Office Washington, DC 20548
August 15, 2006
The Honorable Bill Frist Majority Leader United States Senate
Dear Senator Frist:
Reports by GAO and others in recent years have indicated that increasing
numbers of migrants attempting to illegally enter the United States die
while crossing the southwest border in remote, desert areas or in other
areas with particularly rugged and dangerous terrain. The U.S. Border
Patrol implemented the Border Safety Initiative (BSI) in June 1998 with
the intention of enforcing border security, educating and informing
migrants of the dangers involved in crossing the border illegally, and
carrying out search and rescue operations to help migrants in
lifethreatening situations. Additionally, the Border Patrol implemented
the Arizona Border Control Initiative (ABCI) and the Interior Repatriation
Program (IRP), efforts that also include components designed to reduce
migrant deaths. As part of the BSI's mission, the Border Patrol
established a methodology that outlines procedures to identify, track, and
record data on migrant border-crossing deaths and rescues. The BSI
methodology defines border-crossing deaths as those occurring in
furtherance of an illegal entry and includes guidelines for recording
those deaths occurring within its target zone-an area consisting of 45
counties on or near the southwest border with Mexico.1 These 45 counties
are within an area that includes 9 of the 20 Border Patrol sectors
responsible for enforcing U.S. borders and securing official ports of
entry (see fig. 1). According to BSI reports, since fiscal year 1998,
there has been an upward trend in the number of migrant border-crossing
deaths annually, from 266 in 1998 to 472 in 2005, with some fluctuations
over time.
In light of concerns about reported increases in border-crossing deaths
and interest in the BSI's approach to tracking and reducing these
incidents, you asked us to analyze federal data on border-crossing deaths
as well as available data on the Border Patrol's efforts to reduce such
deaths. Specifically, for this report, we assessed: (1) How do the Border
1
We refer to this area as the BSI target zone.
Patrol's data on trends in the numbers, locations, causes, and
characteristics of border-crossing deaths compare to other sources of data
on these types of deaths? (2) What differences, if any, are there in how
the Border Patrol has implemented the BSI methodology across its sectors?
(3) To what extent do existing data allow for an evaluation of the
effectiveness of the BSI and other Border Patrol efforts to prevent
bordercrossing deaths?
You also asked us to compare deaths among migrants to deaths in the
general U.S. population living within the BSI target zone. We compared
each group's share of deaths for the causes of death most commonly
associated with border-crossing (see app. IV).
To address our objectives, we analyzed data on migrant border-crossing
deaths that occurred between 1990 and 2005 within the BSI target zone-
which includes 45 counties on or near the border in California, Arizona,
New Mexico, and Texas. We analyzed data on border-crossing deaths recorded
by the Border Patrol in the Border Safety Initiative Tracking System
(BSITS) for fiscal years 1998 through 2005. We also analyzed data from the
National Center for Health Statistics (NCHS) mortality files from the
National Vital Statistics System for the years 1990 through 2003, the most
recent year for which NCHS data were available at the time we did our
work. The NCHS data contain information from death certificates for all
deaths occurring within the United States, regardless of the cause of
death. Because death certificates do not explicitly identify deaths as
border-crossing deaths, we used information about place of birth,
residence, and cause of death to identify likely incidents of migrant
deaths. These estimates may either under or over count actual
border-crossing deaths, depending on a number of factors (see app. I for
additional discussion). We assessed the reliability of both sources of
data and determined that they were sufficiently reliable for our purposes
of describing trends in deaths over time and across locations. We then
supplemented our analysis of these data by reviewing data on transient
migrant deaths reported in studies by the University of Houston's Center
for Immigration Research (CIR) that used state vital registry data to
estimate the number of border-crossing deaths among migrants for the
years 1985 through 1998.2 Because both the NCHS and state vital registry
data are collected independently of the Border Patrol's efforts to collect
BSI data, we used them to corroborate or refute the trends that were
identified in our analysis of the BSI data. (For details regarding our
methods for analyzing the data, see app. I.) In addition to the data
analysis, we reviewed the written BSI methodology for tracking and
recording deaths in the BSITS database, and we interviewed Border Patrol
officials at Department of Homeland Security headquarters in Washington,
D.C., as well as officials in the nine southwest Border Patrol sectors,
about issues related to migrant border-crossing deaths and the BSI. We
also reviewed the methods for collecting data on border-crossing deaths
used by county coroners and medical examiners that track these deaths and
reviewed the studies on migrant border-crossing deaths conducted by CIR3,
as well as a study by researchers at the Centers for Disease Control and
Prevention (CDC).4 Finally, we interviewed journalists, officials from
various advocacy groups, and state and local health officials in Arizona,
New Mexico, and California.
We conducted our work between August 2005 and June 2006 in accordance with
generally accepted government auditing standards.
Results in Brief
Our analysis of the BSI and NCHS data shows that both datasets reflect
similar trends in the numbers, locations, causes, and characteristics of
migrant border-crossing deaths between 1990 and 2005. These trends are
consistent with the trends identified in the studies by CIR that used
statelevel vital registry data to document migrant border-crossing deaths
between 1985 and 1998. From the late 1980s through the early 1990s, the
number of border-crossing deaths declined. Then, from the late 1990s
through 2005, the number of deaths approximately doubled. For example,
2
Karl Eschbach, et al., "Causes and Trends in Migrant Deaths along the
U.S.-Mexican Border, 1985-1998," Working Paper No. WPS 01-4. Center for
Immigration Research, University of Houston, Houston, Tex., 2001. Karl
Eschbach, et al., "Deaths During Undocumented Migration: Trends and Policy
Implications in the New Era of Homeland Security," In Defense of the
Alien, Vol. 26, 2003, 37-52. We also reviewed CIR findings as reported in
Belinda I. Reyes, et al., "Holding the Line? The Effect of the Recent
Border Build-up on Unauthorized Immigration," Public Policy Institute of
California, San Francisco, Calif., 2002, 68.
3Eschbach, et al., 2001 and Eschbach, et al., 2003.
4
Sanjeeb Sapkota, et al., "Unauthorized Border Crossing and Migrant Deaths:
Arizona, New Mexico and El Paso, Tex., 2002-2003," American Journal of
Public Health, July 2006.
our analysis of the BSI data shows that the annual number of
bordercrossing deaths increased from 241 in 1999 to a total of 472 deaths
recorded in 2005. Further, the majority of the increase in deaths during
this period occurred within the Border Patrol's Tucson Sector-which
includes much of the Arizona desert. Our analysis of the NCHS data
indicates that, between 1990 and 2003, more than three-fourths of the rise
in migrant border-crossing deaths along the southwest border can be
attributed to an increase in deaths in the Tucson Sector. Over this
period, deaths due to exposure, especially heat-related exposure,
increased substantially, while deaths from traffic fatalities and homicide
declined. This pattern represents a major shift in the causes of migrant
bordercrossing deaths, as traffic fatalities were the leading cause of
migrant border-crossing deaths during the early 1990s, while from the late
1990s onward, heat exposure was the leading cause of death. The increase
in deaths due to heat exposure over the last 15 years is consistent with
our previous report that found evidence that migrant traffic shifted from
urban areas like San Diego and El Paso into the desert following the
implementation of the Southwest Border Strategy in 1994. Our analysis
indicates little change over time in the ages of border-crossing
decedents, and while the majority of decedents are male, the percentage of
female decedents has more than doubled from 1998 to 2005.
Differences in the extent to which the Border Patrol's established
methodology for tracking and recording deaths has been implemented
consistently across its sectors may have led to the BSI data understating
the total number of border-crossing deaths occurring within any given
year. For example, although the BSI methodology instructs BSI sector
coordinators-agents responsible for managing BSI operations within each of
the nine Border Patrol sectors along the southwest border-to maintain
regular contact with local officials such as county coroners and medical
examiners in order to obtain information on any border-crossing deaths
where the Border Patrol was not involved, we found differences among the
sectors in the nature and frequency of the contacts made. Additionally,
methods for coordinating with local officials have not yet been formalized
in some sectors. These sectors are in locations in which relatively few
border-crossing deaths occur, and as a result, the informal communication
patterns may have had little impact on the total numbers of deaths
recorded in the BSI data thus far. However, these trends have the
potential to change in the future, as they did in the Tucson Sector
between 1998 and 2005. According to our analysis of the BSI data, the
number of deaths in the Tucson Sector increased from 11 in 1998 to 216 in
2005. Irregular communication, as well as variation in the nature and
frequency of contacts with local officials, may lead to inconsistencies in
tracking and recording deaths over time and across sectors and could
ultimately result in the Border Patrol's data on border-crossing deaths
being incomplete. Such incomplete data may in turn affect the Border
Patrol's ability to understand the scale of the problem in each sector and
affect the agency's ability to make key decisions about where and how to
deploy BSI resources across the southwest border.
Measurement challenges and data limitations inhibit a comprehensive
evaluation of the BSI's efforts to prevent border-crossing deaths.
Furthermore, there is insufficient evidence to support the Border Patrol's
assertions that related efforts such as the ABCI and IRP reduced migrant
deaths between 2003 and 2004. The effectiveness of the Border Patrol's
efforts to prevent deaths cannot simply be measured by examining changes
in the number of migrant deaths following the introduction of a prevention
effort, as other factors may also affect the number of deaths. For
example, changes in the number of migrants attempting to cross the border,
variations in the locations where migrants attempt to cross, fluctuations
in weather patterns, and changes in Border Patrol enforcement activities
may all affect the number of border-crossing deaths in any given year. The
effects of such factors on the number of migrant deaths need to be taken
into account when assessing the impact of the BSI and related efforts. In
addition, evaluating the BSI's efforts to prevent deaths is further
limited by the extent to which the Border Patrol can accurately measure
the hours and resources dedicated exclusively to the BSI and other
prevention activities. As the Border Patrol is primarily an enforcement
agency, search and rescue activities often occur simultaneously with
enforcement activities, thus making it difficult to separate the resources
dedicated to each type of activity. The Border Patrol's assertions that
its prevention efforts have resulted in a reduction in migrant deaths have
not taken such factors into account. In the absence of using multivariate
statistical methods that control for the influences of other measurable
factors, the effectiveness of these programs' impact on border-crossing
deaths cannot be demonstrated.
In order to improve the implementation of the BSI methodology and the
accuracy of the data on migrant border-crossing deaths in any given year,
we recommend that the Commissioner of Customs and Border Protection take
steps to ensure that BSI sector coordinators follow a consistent protocol
for collecting and recording information about border-crossing deaths and
that all coordinators follow established procedures for maintaining and
documenting regular contacts with local authorities.
In order to better demonstrate the effectiveness of the Border Patrol's
efforts to reduce migrant deaths, we recommend that the Commissioner of
Customs and Border Protection assess the feasibility and costeffectiveness
of using multivariate statistical approaches to enhance estimates of the
impacts of its initiatives.
We provided a draft of this report to the Departments of Homeland
Security, Health and Human Services, Justice, and State for review and
comment. On July 20, 2006, we received written comments on the draft
report from the Department of Homeland Security (DHS), which are
reproduced in full in appendix V. DHS concurred with our findings and
outlined plans to address both of the recommendations. In its letter, DHS
noted that because the Office of Border Patrol is an enforcement agency,
Border Patrol agents exercise daily border safety functions in the course
of carrying out their priority mission and that apprehending illegal
aliens before they come into distress diminishes the risk involved with
illegally crossing into the United States. We agree with this statement;
one of the confounding issues to measuring the outcomes of border safety
initiatives is that border enforcement and border safety are
interconnected. DHS and the Department of Health and Human Services also
provided a number of technical comments and clarifications, which were
incorporated into the report as appropriate. The Departments of Justice
and State did not have comments on the draft.
Background
In 1994, the Attorney General announced plans for the Southwest Border
Strategy, an enforcement initiative designed to strengthen enforcement of
the nation's immigration laws and to shut down the traditional corridors
for the flow of illegal immigration along the southwest border. The
strategy called for the former Immigration and Naturalization Service
(INS)5 to incrementally increase control of the border in four phases with
the goal of making it increasingly difficult and costly for migrants to
attempt illegal entry so that fewer individuals would try. The strategy
called for adding resources along the southwest border by first
concentrating personnel and technology in those sectors with the highest
levels of illegal immigration activity (as measured by apprehensions) and
by then moving to the areas with the least activity. Additional Border
5
Following the creation of DHS in 2003, the former INS was 1 of 22 federal
agencies brought together within DHS. INS functions related to border
security were assumed by
U.S. Customs and Border Protection under the newly created DHS.
Page 6 GAO-06-770 Border-Crossing Deaths
Patrol resources were initially allocated in the San Diego, California,
and El Paso, Texas, sectors. The strategy assumed that as the urban areas
were controlled, the migrant traffic would shift to more remote areas
where the Border Patrol would be able to more easily detect and apprehend
migrants entering illegally. The strategy also assumed that natural
barriers including rivers, such as the Rio Grande in Texas, the mountains
east of San Diego, and the desert in Arizona would act as deterrents to
illegal entry (see fig. 1).
Figure 1: Border Patrol Sectors and the BSI Target Zone along the United
States-Mexico Border
California
Arizona
New Mexico
Texas
Oklahoma
El Centro
San Diego
San
Desert
Diego
Del Rio
El Paso
Laredo
Sonoran Desert
Rio Grande Valley
Rio
Pacific
Grande
Ocean MEXICO River
Border Patrol sector boundariesState boundariesBSI target zone Higher
elevationsand mountainousareasIncorporated cities
Source: GAO; U.S. Border Patrol.
Notes: Solid lines are used where state and sector boundaries overlap. The
Rio Grande River flows south through New Mexico, along the border between
Texas and Mexico, and into the Gulf of Mexico.
As we reported in 2001, INS' analysis of apprehensions data indicated that
the increased enforcement efforts in the San Diego and El Paso sectors
that began in 1994 ultimately resulted in the redirection of migrant flows
to eastern California and the Sonoran Desert of Arizona.6 However, INS did
not anticipate the sizable number of migrants that would continue to
attempt to enter the United States through this harsh terrain. Studies of
migrant deaths along the southwest border at the time concluded that,
while migrants had always faced danger crossing the border and many died
before INS began the Southwest Border Strategy, following the
implementation of the strategy, there was an increase in border-crossing
deaths resulting from exposure to either extreme heat or cold.
The Border Patrol Implemented the Border Safety Initiative in June
In response to concerns about the number of migrants who are injured or
die while attempting to cross the border, the INS implemented the Border
Safety Initiative (BSI) and a number of related programs beginning in June
1998. These initiatives were implemented in conjunction with the Border
Patrol's ongoing enforcement efforts; the Border Patrol views the BSI and
related efforts to prevent deaths as complementary to its primary mission
of enforcing the law and securing the border. The primary objectives of
the BSI are to reduce injuries among migrants and to prevent migrant
deaths in the southwest border region. Many migrants suffer severe
dehydration and heat exhaustion as a result of attempting to cross the
desert where temperatures can exceed 115 degrees in the summer. Agents
provide assistance to migrants who are stranded and may supply food,
water, and medical care to migrants who become injured or lost in the
course of attempting to cross the border.
As part of the BSI's efforts to prevent migrant deaths, several of the
Border Patrol sectors in the BSI target zone have rescue beacons installed
in those areas of the desert considered to be especially dangerous for
migrants attempting to cross the border. Each beacon has a button that
migrants can push to activate a sensor, thus alerting nearby Border Patrol
agents that they are in need of help. Each sector also has a number of
specialized search and rescue units known as Border Patrol Search, Trauma,
and Rescue (BORSTAR) teams. BORSTAR agents have specialized training in a
number of areas including medical skills, technical rescue, navigation,
communication, swiftwater rescue, and air operations in order to prepare
them to carry out emergency search and rescue operations. BORSTAR units
conduct search and rescue operations as part of the Border Patrol's
6
GAO, INS' Southwest Border Strategy: Resource and Impact Issues Remain
after Seven Years, GAO-01-842 (Washington, D.C.: August 2001).
Page 9 GAO-06-770 Border-Crossing Deaths
ongoing efforts to enforce and secure the border. As of October 2005, the
Border Patrol had deployed 164 BORSTAR agents within its nine Border
Patrol sectors along the southwest border.
The Interior Repatriation Program (IRP) and Lateral Repatriation Program
(LRP) are additional initiatives designed by the Border Patrol to prevent
deaths and to discourage migrants from crossing the border in dangerous
areas of the desert. The IRP was implemented in 2004 in conjunction with
the Mexican government with the goal of removing migrants from those areas
considered to be smuggling corridors in an effort to break the cycle of
illegal immigration among those migrants who make repeated attempts to
cross the border following apprehension. The program transports migrants
who are apprehended in the Tucson and Yuma Sectors, and who volunteer for
the program, to their hometowns in the interior of Mexico, rather than
deporting them to points along the Arizona border where they may be more
likely to attempt to cross again. Similarly, the LRP was implemented when
the United States was unable to negotiate an agreement to return migrants
to the interior of Mexico with the Mexican government in September 2003.
Migrants apprehended in Arizona were instead transported to ports of entry
in Texas in an effort to discourage them from attempting multiple
crossings in the desert.
In response to the escalating problems with illegal immigration in
Arizona, the Border Patrol also implemented the Arizona Border Control
Initiative (ABCI) in 2004 as a multi-disciplinary initiative with the goal
of coordinating federal, state, and local authorities to control the
Arizona border. The ABCI strategy focused on confronting illegal
immigration along the western part of the Arizona desert before it reached
the United States. Components of the program included a media campaign
warning migrants of the dangers associated with crossing the border and
increased infrastructure and manpower along the Arizona border. While not
intended primarily as a safety initiative, the enhanced infrastructure and
increased manpower associated with the ABCI also allowed Border Patrol
officers to better track and rescue migrants and to prevent deaths.
Additional components of the program include roving patrols, camp details,
and air support, and included increased assistance with highway patrols
from state, local, and tribal authorities.
The Border Patrol has also implemented a number of additional efforts to
discourage migrants from attempting to cross the border as part of the
BSI's prevention component. Prevention efforts have included broadcasting
public service announcements in Mexico about the risks involved in hiring
smugglers and posting signs in high-risk areas to warn
potential crossers of the dangers at the border. Because many migrants
attempting to enter the United States illegally may not carry
identification, the BSI also attempts to identify those who have died
while crossing the border. Border Patrol officers work in conjunction with
Mexican Consulates in the region in order to identify migrants who may
have been reported missing by friends or family.
In 2000, the BSI also began formally tracking and recording data on
migrant rescues and deaths through the establishment of a database known
as the Border Safety Initiative Tracking System (BSITS). BSI data are used
by the Border Patrol for tracking numbers and locations of deaths and
rescues, identifying trends and high-risk areas, allocating resources for
BSI projects, and measuring the effectiveness of various programs and
projects that are related to the BSI. The database includes information
such as cause and location of death as well as the decedent's gender and
nationality. In order to ensure consistent tracking and recording of
incidents along the southwest border, the BSI has developed a formal,
written methodology that outlines the roles and responsibilities of each
BSI sector coordinator in collecting and recording data on migrant deaths
and rescues. The methodology also outlines definitions for the types of
incidents that should be recorded in the BSITS database. The methodology
defines a BSI-related death as a death involving an undocumented migrant
in furtherance of illegal entry within the BSI target zone, or deaths
occurring outside the target zone when the Border Patrol was directly
involved. The methodology includes detailed instructions regarding the
time frame for reporting incidents, protocols for entering and updating
information recorded in BSITS, and guidelines for coding incidents using
appropriate rescue and cause of death categories. In order to ensure that
all migrant border-crossing deaths in the target zone are reported, the
methodology also specifies that BSI sector coordinators should establish
contact with local medical examiners or county coroners as well as Mexican
Consulates in the region about those deaths where the Border Patrol was
not involved in order to record the deaths in the BSITS database.
Various Groups Track and Record Border-Crossing Deaths Using Different
Methodologies That Can Lead to Differing Counts of Deaths
A number of groups in addition to the Border Patrol have also attempted to
track incidents of border-crossing deaths. Advocacy groups, media outlets,
medical examiners' offices in some border counties, researchers at the
CDC, and the Mexican government are among the organizations that have
collected and reported data on border-crossing deaths, but each uses a
different methodology to count and record deaths. All agree that a
border-crossing death involves a migrant who dies in the course of
Page 11 GAO-06-770 Border-Crossing Deaths
attempting to cross illegally into the United States. However, each may
operationalize the definition differently and rely on a variety of sources
of information for making determinations about which deaths to include in
their counts. For example, the "Victoria 19"-an incident in which 19
migrants who were smuggled in the back of a tractor-trailer were all found
to have suffocated near Victoria, Texas, in 2002-would not be included in
the Border Patrol's counts of migrant border-crossing deaths because it
occurred outside the BSI target zone and there was no direct Border Patrol
involvement in the case.7 By contrast, some advocacy groups that track and
record border-crossing deaths include the Victoria 19 in their totals.
Because the incident involved migrants who were in transit across the
border into the United States, they consider it a border-crossing death,
even though it occurred outside the Border Patrol's identified BSI target
zone.
In making decisions about whether or not to count the death of an
unidentified person as a border-crossing death, Border Patrol officials
and others may rely on professional judgment of circumstantial evidence.
This may also result in differing counts of deaths from one group to the
next. For example, data on border-crossing deaths maintained by the Pima
County Medical Examiner's office for the Tucson area have been cited by
the media in news reports. Some cases of border-crossing deaths may
involve unidentified bodies that were discovered in the desert; these
cases can often include skeletal remains or decomposed bodies. In
determining whether to count these incidents as border-crossing deaths,
the Pima County Medical Examiner's office uses information about where a
body is found-for example, along a known migrant corridor-as well as other
circumstantial evidence such as the decedent's clothing or personal
effects that may indicate a country of origin. The Pima County Medical
Examiner's office reported that it records all cases of migrant deaths
including a few cases involving migrants who die of natural causes such as
heart attacks or appendicitis, noting that, if there is evidence that the
person died while in transit between Mexico and the United States, the
office will count it as a border-crossing death regardless of the cause.
However, the Pima County Medical Examiner's office places some limitations
on which cases it records as border-crossing deaths. For example, the
office attempts to exclude any cases involving illegal immigrants who had
established residency in the United States from its
Victoria, Texas, lies within Victoria County, which is within the Border
Patrol's Rio Grande Valley Sector. However, it is not 1 of the 45 counties
that comprise the BSI target zone.
Page 12 GAO-06-770 Border-Crossing Deaths
counts of border-crossing deaths in order to distinguish deaths occurring
among illegal immigrants who had been living and working in the United
States for some time from migrants who died in the course of attempting to
cross the border.
Using another method to measure migrant border-crossing deaths,
researchers at the CDC designed a study to track and record migrant
border-crossing deaths occurring in U.S. border counties in Arizona, New
Mexico, and Texas between 2002 and 2003.8 They requested that medical
examiners in these states provide them with information about cases that
met a number of standardized criteria. The researchers then reviewed the
death certificates and other information about these cases in order to
describe trends in border-crossing deaths. They asked medical examiners to
include only those cases involving decedents who were found in one of
several selected U.S. counties along the U.S. border with Mexico, whose
immigration status was determined to be unauthorized, and who were
determined to have died during transit from Mexico into the United States
within 30 days of their arrival in the country. According to their
methodology, an unauthorized decedent was identified based upon one or
more of the following criteria: a person who was identified as not being a
legal resident or an authorized entrant into the United States, a person
who was identified as a resident of another country based upon reports by
family, friends, or officials, or a person who was identified as being a
resident of another country based upon analysis of circumstantial evidence
found with the decedent. Such circumstantial evidence included tattoos,
items found on or near the body, personal items found in bags, clothes,
and documents including birth and marriage certificates. Decedents were
not included in the study if they were known to have resided illegally in
the United States for more than a month before their death, if they were
determined not to have died while crossing the border, or if they had died
after being treated in a U.S. border hospital.
Table 1 illustrates the counts recorded by some of the groups attempting
to track and record border-crossing deaths in Pima County, Arizona,
between 2002 and 2005.
Sapkota, et al., 2006.
Table 1: Number of Migrant Border-Crossing Deaths Occurring in Pima
County, Arizona, as Reported by Various Sources, 2002 through 2005
Year Source 2002 2003 2004 2005
a a
Sapkota, et al. 139 131
Pima County Medical Examiner 139 131 130 155
BSI data 95 75 84 154
Sources: GAO analysis of data in Sapkota, et al., 2006 and of BSI data;
Pima County Medical Examiner data.
a
The Sapkota, et al., study was limited to deaths occurring during 2002 and
2003; hence, figures for these years are not available.
BSI and NCHS Data Show That, Since the Late 1990s, Increases in Deaths
along the Southwest Border Were Accounted for by Increases in Deaths in
the Tucson Sector
Our analysis of the BSI and NCHS data shows consistent trends in the
numbers, locations, causes, and characteristics of deaths over time.
Consistent with reported trends in prior studies of border-crossing
deaths, our analysis of both data sources shows an increase in the overall
numbers of deaths occurring along the southwest border between 1998 and
2005 following a decline between 1990 and 1994. Our analysis of the NCHS
data shows that the number of deaths doubled from the mid-1990s through
2003, and our analysis of the BSI data shows that the majority of the
increase in deaths that occurred between 1998 and 2005 was concentrated
within the Border Patrol's Tucson Sector. Consistent with the increase in
Tucson, the number of border-crossing deaths due to heat exposure also
steadily increased beginning in 1998. While the majority of deaths have
occurred among men, according to our analysis of the BSI data, deaths
among women increased from 9 percent of all deaths in 1998 to 21 percent
of all deaths in 2005.9 Further, increases in deaths among women in the
Tucson Sector accounted for the majority of the overall increase in deaths
among women in all sectors. The increase in the number of deaths in the
Tucson Sector between 1998 and 2005 occurred despite the fact that the
number of apprehensions of illegal immigrants recorded by the Border
Patrol in the Tucson Sector had declined following a peak in 2000. To the
extent that apprehensions are correlated with the number of attempted
crossings, the increase in deaths in the Tucson Sector indicates that the
desert is a particularly difficult region for migrants attempting illegal
entry.
9
Our analysis of NCHS data shows that deaths among women increased from 12
percent of all deaths in 1998 to 26 percent of all deaths in 2003, the
most recent year for which data are available.
Page 14 GAO-06-770 Border-Crossing Deaths
BSI and NCHS Data Show Consistent Trends in Numbers, Locations, and Causes
of Death
Our analysis of the BSI data as well as our analysis of the NCHS data
reveals trends that are consistent with trends identified in previous
studies by CIR examining the numbers, locations, and causes of
border-crossing deaths over time. All three sources of data show that
trends in migrant deaths follow a somewhat U-shaped curve as deaths within
the BSI target zone increased beginning in the mid-1990s following a
period of decline between 1990 and 1994 (see fig. 2). We used NCHS
data-which are based on death certificates filed by local coroners and
medical examiners throughout the country and include records of all deaths
that occur within the United States, regardless of the decedent's country
of origin-as an independent data source to corroborate trends identified
in the BSI data.10 Additionally, the trends in the NCHS data between 1990
and 1998 are also consistent with the trends in border-crossing deaths
reported by Karl Eschbach and his colleagues at the Center for Immigration
Research in their analysis of state-level vital registry data. Differences
in the total numbers of deaths in the NCHS and CIR data arise from the
differences in the methodologies used by each.11 Our analysis of the NCHS
data shows that deaths declined in the San Diego and El Centro Sectors
between 1990 and 1994 and that over this period, deaths from traffic
fatalities and homicide also declined. This pattern represents a major
shift in the causes of migrant border-crossing deaths, as traffic
fatalities were the leading cause of migrant border-crossing deaths during
the early 1990s, while from the late 1990s onward, heat exposure was the
leading cause of death. Additionally, according to our analysis of the
NCHS data, homicides decreased from 24 percent of all deaths in 1990 to 9
percent in 2003. Our analysis of the BSI data also shows that heat
exposure was the leading cause of death from 1998 to 2005. The increase in
deaths due to heat exposure over the last 15 years is consistent with our
previous report that found evidence that migrant traffic shifted from
urban areas like San Diego and El Paso into the desert following the
implementation of the Southwest Border Strategy in 1994.12
10
Our counts differ from Border Patrol reports due to differences in
methodology. See app. I for details about our methodology.
11
Our analysis of the NCHS data includes deaths in the 45 counties that make
up the BSI target zone, while CIR's analysis includes a total of 55
counties on or near the southwest border with Mexico. Additional
differences between the two data sources include the codes used to
identify common causes of migrant deaths. See app. 1 and Eschbach, et al.,
2003, for additional discussion.
12GAO-01-842.
Figure 2: Migrant Border-Crossing Deaths in the BSI Target Zone, 1985
through 2005
Number of deaths
100
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR findings, as reported in
Reyes, et al., 2002, 68.
Notes: BSI data are arrayed on a fiscal year basis, while NCHS data and
CIR findings are on a
calendar year basis. Annual totals for CIR findings are based on cause of
death counts as reported in
Reyes, et al., 2002, 68. CIR findings include data from 55 counties.
Our analysis of the BSI data shows that the total number of border
crossing deaths increased from 254 in 1998 to 334 in 2003 and then
increased to 472 in 2005.13 Similarly, our analysis of the NCHS data shows
that the number of deaths increased from 219 in 1998 to 365 in 2003.
Corresponding with the increases in deaths that occurred between 1998
and 2005, border-crossing deaths also became increasingly concentrated
within the Tucson Sector-a region that corresponds with Arizona's
portion of the Sonoran Desert. For example, our analysis of the BSI data
shows that the Tucson Sector's share of all border-crossing deaths
increased tenfold, from 4.3 percent of all deaths in 1998 to 45.8 percent
in
2005 (see fig. 3), so that by 2005, of the 472 deaths that occurred across
all
13Border Patrol reported a total of 291 deaths during the first 9 months
of fiscal year 2006 (October 1, 2005, through June 30, 2006). Our analysis
of the BSI data for the first 9 months of fiscal year 2005 (October 1,
2004, through June 30, 2005) shows a total of 241 deaths.
Page 16 GAO-06-770 Border-Crossing Deaths
nine southwest sectors, 216 occurred within the Tucson Sector. Our
analysis of the NCHS data shows a similar trend, in that the Tucson
Sector's share of border-crossing deaths increased at least threefold
between 1998 and 2003. The total number of deaths in the eight other
Border Patrol sectors remained relatively constant over this period.14
Figure 3: Percentage of All Migrant Border-Crossing Deaths in the BSI
Target Zone Occurring within the Tucson Sector, 1985 through 2005
Percentage of all deaths
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR findings, as reported
in Reyes, et al., 2002, 68and Eschbach, et al., 2001, 24-61.
Notes: BSI data are arrayed on a fiscal year basis, while NCHS data
and CIR findings are on a
calendar year basis. CIR findings exclude deaths from unknown causes.
Further, the increase in deaths occurring within the Tucson Sector
accounted for the majority of the increase in deaths along the
southwest
border. For example, our analysis of the NCHS data indicates that the
increase in deaths in the Tucson Sector from 1990 to 2003 accounted
for
more than 78 percent of the total increase in border-crossing deaths
along
the entire southwest border. Across all sectors during these years,
the
total number of border-crossing deaths increased by 195, and of that
14
For the number of deaths in each sector, see figs. 8 through 16 in app.
II.
increase, 153 deaths occurred in the Tucson Sector. Our analysis of the
BSI data shows a similar result: between 1998 and 2005, deaths across all
sectors increased by 218, and the Tucson Sector accounted for 205-or 94
percent-of the increase. The increase in deaths in the Tucson Sector is
also consistent with the shifting of migrant traffic from urban areas in
San Diego and El Paso into the desert following the implementation of the
Southwest Border Strategy. The increase in deaths in the Tucson Sector
occurred after the number of deaths occurring within the San Diego Sector
declined, beginning in the early 1990s (see fig. 8 in app. II). In 1990,
the San Diego Sector accounted for over one-third of all border-crossing
deaths. By 2003, the San Diego Sector accounted for only 8 percent of all
deaths.
While much of the migrant traffic appears to have shifted to sectors east
of San Diego like Tucson, a similar shift does not appear to have occurred
in the sectors east of El Paso. Border Patrol officials have noted that
there are few population centers on the Mexican side of the border in
those regions that might serve as a starting point for migrants intending
to cross. Similarly, on the U.S. side of the border, sectors like Marfa in
western Texas are more sparsely populated. Border Patrol officials have
speculated that fewer migrants attempt to cross in these areas because
they largely consist of small towns and communities. Consequently,
migrants may have to walk longer distances to reach a population center
and may face an increased risk of being apprehended as a result of being
noticed by the local population or Border Patrol agents.
As the number of deaths occurring within the desert in and around the
Tucson Sector increased, so too did the number of deaths due to heat
exposure. While there has been an overall increase in the number of heat
exposure deaths between 1994 and 2005, there have been some fluctuations
between years. These fluctuations may be due to factors such as
temperature changes from one year to the next as higher desert
temperatures in some summers may result in an increase in migrant deaths.
Our analysis of both the BSI and NCHS data shows increases in the total
percentage of border-crossing deaths due to heat exposure over time. For
example, by 2001, heat exposure deaths in the BSI data accounted for more
than one-third of all deaths. Our analysis of the NCHS data also shows
that by 2001 heat exposure deaths accounted for more than 30 percent of
all border-crossing deaths, an increase from about 4 percent in 1990 (see
fig. 4).
Figure 4: Percentage of All Migrant Border-Crossing Deaths in the BSI
Target Zone Due to Heat Exposure, 1985 through 2005
Percentage of all deaths
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR findings, as reported
in Reyes, et al., 2002, 68.
Notes: BSI data are arrayed on a fiscal year basis, while NCHS data
and CIR findings are on a
calendar year basis. CIR findings include data from 55 counties and
deaths from all environmental
causes, such as heat exposure and hypothermia.
As the number of deaths due to heat exposure increased, the number of
deaths due to traffic-related fatalities, homicide, and drowning
either
remained relatively constant or declined (see fig. 5). 15 For
example, our
analysis of the NCHS data shows that traffic fatalities declined from
more
than half of all border-crossing deaths in the early 1990s to less
than
30 percent of deaths by 2003. Our analysis of the BSI data shows
similar
trends, with deaths due to exposure increasing from 107 to 185 while
deaths due to motor vehicle accidents, homicide,16 and drowning
15
See app. III for causes of death according to BSI data and the CIR
findings.
16
This figure also includes deaths from suicide and Border Patrol shootings.
decreased slightly from 109 to 103 between 1998 and 2005.17 Our analysis
of the NCHS data also shows that homicides have also declined slightly,
accounting for 41 border-crossing deaths in 1990, and 33 deaths in 2003.
Despite the decline in homicides, Border Patrol officials have noted an
increase in border-related violence among smugglers and migrants including
assault and robbery, though officials stated that few incidents have
resulted in deaths thus far.
Figure 5: Migrant Border-Crossing Deaths, by Cause of Death, NCHS Data,
1990 through 2003 Number of all deaths200 180 160 140 120 100 80
60 40 20 0
1990 1991 1992 19931994 1995 1996 1997 19981999 2000 2001 2002 2003
Year of death
Motor vehicle accidentsAll exposure, heat and cold Homicide Drowning
Pedestrian deaths from vehicular traffic
Source: GAO analysis of NCHS data.
17
These totals do not reflect unknown cases recorded by the Border Patrol
that may include skeletal remains for which the cause of death could not
be determined. Our analysis of the data shows that unknown causes of death
as recorded in BSITS have increased from 11 percent in 1998 to 36 percent
in 2005.
Page 20 GAO-06-770 Border-Crossing Deaths
Risk Associated with Border Crossing Appears to Have Increased in Recent
Years
The risk associated with attempting to cross the border illegally also
appears to have increased between 1998 and 2004. While the number of
migrant border-crossing deaths approximately doubled over this period,
estimates of undocumented migration into the United States-whether based
on U.S. census data or based on the number of Border Patrol apprehensions
of migrants attempting illegal entries-do not show a corresponding
increase. For example, estimates of illegal entries into the United States
indicate that from 1998 through 2004, the estimated number of such entries
has declined by 16 percent. Similarly, the number of apprehensions of
persons attempting illegal entry has declined by 25 percent over this same
period. At the same time, our analysis of the BSI data shows that the
number of border-crossing deaths increased by about 29 percent from 254 in
1998 to 328 in 2004. (See app. I for a discussion of our methodology.) An
examination of the increase in the number of deaths in relation to
declines in the estimated number of illegal entries suggests that the risk
associated with crossing the border has increased in recent years.
This apparent increase in risk associated with attempting to cross the
border illegally also appears to be concentrated in the Tucson Sector. The
increase in the number of border-crossing deaths from 1998 through 2005
was generally independent of changes in the number of apprehensions of
migrants attempting illegal entries within the sector, especially during
the decline in apprehensions that occurred between 2000 and 2002 (see fig.
6). In other sectors, the number of apprehensions generally correlated
with the number of deaths: as apprehensions increased, deaths show a
corresponding increase, and conversely, as apprehensions declined, deaths
generally also declined, although the amount of change in deaths and
apprehensions between years differed (see fig. 7).
Figure 6: Migrant Border-Crossing Deaths and Apprehensions in the BSI
Target Zone Occurring within the Tucson Sector, Fiscal Years 1998 through
2005
Number of deathsNumber of apprehensions250 700,000
200
600,000
150
500,000
100
400,000 50
0 300,000
1998 1999 2000 2001 2002 2003 2004 2005
Year of
death
Deaths
Apprehensions
Source: GAO analysis of BSI and U.S.
Border Patrol data.
Note: Data are for fiscal years
beginning October 1.
Figure 7: Migrant Border-Crossing Deaths and Apprehensions in the BSI
Target Zone Occurring within All Sectors except Tucson, Fiscal Years 1998
through 2005
Number of deathsNumber of apprehensions300 1,200,000
150 500,000
1998 1999 2000 2001 2002 2003 2004 2005
Year of
death
Deaths
Apprehensions
Source: GAO analysis of BSI and U.S. Border Patrol
data.
Note: Data are for fiscal years beginning October 1.
While there are limitations to using the number of
apprehensions as a
measure of attempted illegal entries into the United
States, we previously
reported that changes in apprehensions can provide
some evidence of
shifting illegal migration patterns.18 However, to
the extent that
apprehensions can be used as an indication of
attempted illegal entries
into the United States, unlike other estimates of
illegal entries, these data
have the advantage of being sector-specific and,
therefore, allow for
comparisons between sectors in estimating attempted
illegal entries and
deaths. In the Tucson Sector, apprehensions
increased from 1998 to 2000
and then generally declined from 2000 to 2005, with
some year-to-year
fluctuations. While apprehensions generally
declined, the number of
border-crossing deaths in the Tucson sector
continued to increase over
the same period. To the extent that an increased
number of apprehensions
18For a discussion of limitations, see GAO, Illegal Aliens: Despite Data
Limitations, Current Methods Provide Better Population Estimates,
GAO/PEMD-93-25 (Washington, D.C.: August 1993). For a discussion of
apprehensions as evidence for shifting migration patterns, see GAO-01-842.
Page 23 GAO-06-770 Border-Crossing Deaths
generally can be assumed to represent an increased number of migrants
attempting illegal entry, the inverse relationship between apprehensions
and deaths in Tucson suggests that deaths have increased despite the fact
that there has not been a corresponding increase in the number of people
attempting to cross in that sector.
The reasons for this phenomenon are unclear. There are a number of factors
that may make the desert in and around Tucson a particularly dangerous
region for migrants to navigate, including the difficulty of the terrain,
extreme summer temperatures, and the increased use of smugglers in the
sector. While there is evidence that increasing numbers of migrants have
employed smugglers to help them cross the border illegally across all nine
southwest Border Patrol sectors in recent years, smuggling may be
especially dangerous in the Tucson Sector. Border Patrol officials
reported that migrants who are unable to keep up with smugglers may be
left behind in extreme desert temperatures without sufficient food or
water. Alternatively, the inverse relationship between apprehensions and
deaths in the Tucson Sector could arise if apprehending migrants has
become more difficult in Tucson than in other sectors. This could result
from a number of factors such as changes in the number of agents assigned
to patrol the sector or the number of migrants who are able to evade
apprehension by attempting to cross in particularly remote areas of the
sector.
While the Majority of Border-Crossing Deaths Occur among Men, the Increase
in Deaths among Women Occurred Largely in the Tucson Sector
According to our analysis of the NCHS data, males comprised more than 78
percent of the border-crossing deaths occurring between 1990 and 2003, and
persons between 15 and 44 years of age comprised 79 percent of all deaths.
The trends over time in these respective shares of deaths were relatively
constant with some minor, year-to-year fluctuations. Our analysis of the
BSI data shows similar trends between 1998 and 2005, with males accounting
for 83 percent of all deaths, and persons between the ages of 15 and 44
comprising 88 percent of all deaths. This was true across all sectors with
trends remaining relatively constant across years. While deaths among
women were consistently much lower than men, there was an increase in the
overall number of female deaths that occurred between 1998 and 2005-the
number of female deaths increased from 22 to 90, or from 9 percent to 21
percent of all deaths. Our analysis of the BSI data shows that, between
1998 and 2005, the increase in deaths among females in the Tucson Sector
accounted for 57 percent of the total increase in deaths among women
across all sectors. Similarly, our analysis of the NCHS data shows that
from 1990 to 2003, the increase in deaths among
females in the Tucson Sector accounted for 96 percent of the total
increase in deaths among women across all sectors.19
The Border Patrol's Approach to Tracking and Recording Deaths Has Not Been
Implemented Consistently across Sectors
The BSI's methodology for collecting data on border-crossing deaths
provides a framework for gathering and recording data on the number of
migrant deaths that occur in each sector. While the Border Patrol has
taken steps to improve the collection of its data over time, differences
remain among the nine BSI sector coordinators in how each has implemented
the methodology, and these differences could result in incomplete counts
of border-crossing deaths in any given year. Additionally, because of
inherent uncertainties associated with determining whether some migrant
deaths are border-crossing deaths, an exact count of all deaths may not be
possible to obtain.
Differences in the Implementation of the BSI Methodology across Sectors
May Result in Incomplete Counts of Border-Crossing Deaths
The BSI methodology specifies that each sector coordinator should track
all migrant deaths occurring within the sector, including those deaths
that may have first come to the attention of local authorities by
obtaining and sharing information with county coroners or medical
examiners. However, BSI sector coordinators have the latitude to decide
how to implement this outreach. Some coordinators reported regularly
scheduled contact with local authorities, while others stated that
communication was informal and infrequent. Some coordinators also reported
that the nature and methods for communicating with local authorities had
changed from one year to the next. For example, local medical officials in
one county where a relatively large number of deaths occurred reported
that Border Patrol officials in the Tucson Sector only began contacting
them in 2005 to request information on border-crossing deaths. As a
result, the BSI data prior to that year may not have included records of
those border-crossing deaths that were discovered by local authorities but
that did not come to the attention of Border Patrol officials. To the
extent that they may not include data on all border-crossing deaths
recorded by local officials, the BSI data may represent an undercount of
the total number of bordercrossing deaths in that sector. These
undercounts may affect the Border Patrol's ability to understand the scale
of the problem in each sector and
19
Children appear to only represent a small share of deaths along the
border. Our analysis of the BSI data shows that persons under the age of
15 comprised less than 2 percent of all deaths from 1998 to 2005. This was
true across all sectors with trends remaining relatively constant from
year to year. Our analysis of the NCHS data shows that persons under the
age of 15 comprised about 3 percent of all deaths from 1990 to 2003.
Page 25 GAO-06-770 Border-Crossing Deaths
also impact its ability to continue to make accurate resource allocations
along the southwest border.
Since January 2005, the National BSI Coordinator has taken steps to
further clarify the methods that sector coordinators should use to
collaborate with local officials in collecting BSI data. However, the
revised BSI methodology does not specify the frequency with which sector
coordinators are to conduct this outreach nor does it outline the methods
that coordinators should use to share information about migrant deaths
with county coroners or local medical examiners. While all coordinators
reported some degree of contact with local authorities, communication
remains informal in some sectors. As a result, Border Patrol officials in
these sectors may not learn about all cases of migrant deaths,
particularly in smaller counties where border-crossing deaths occur with
less frequency. Border Patrol officials in those sectors reporting
informal or infrequent communication stated that they did not believe that
these omissions would likely have a significant impact on the total number
of deaths recorded in the BSITS database. While our analysis of the NCHS
data confirms these sectors have had relatively few deaths in recent
years, those trends have the potential to change in the future. For
example, our analysis of the BSI data shows only 11 deaths in the Tucson
Sector in 1998. However, as migration shifted from the San Diego Sector to
the Tucson Sector following the implementation of the Southwest Border
Strategy, the number of deaths in Tucson increased significantly. By 2005,
Tucson accounted for nearly half of all deaths recorded across all nine
sectors, with a total of 216 deaths. Since the current BSI methodology
gives each sector coordinator the latitude to determine how to approach
communication with local authorities about border-crossing deaths,
differences between sectors in implementing the BSI methodology may
ultimately affect the Border Patrol's counts of border-crossing deaths in
the future. In addition, the nature and frequency of each sector's contact
with local officials could potentially change each time a new sector
coordinator is assigned.
Identifying Border-Crossing Deaths May Be Difficult in Some Cases
Another factor that may affect the extent to which the Border Patrol
records the precise number of border-crossing deaths is the uncertainty
that arises in those cases involving bodies discovered in the desert or
other remote areas. In some of these instances both Border Patrol agents
and local medical examiners must use their professional judgment in
determining whether circumstantial evidence is sufficient to classify a
decedent as a migrant who died while in furtherance of an illegal entry.
Both Border Patrol officials and local medical examiners with whom we
spoke reported relying on such evidence as the type of clothing worn by
the decedent, whether or not the person was carrying water jugs (as
evidence that the person intended to travel some distance on foot), as
well as any personal documents or identification that might indicate
country of origin. Border Patrol officials and others also reported that,
in many cases where the decedent had no identification or only skeletal
remains were found, they may conclude that the decedent was a migrant
attempting illegal entry because the remains were found in a remote area
that was a known migrant-crossing corridor.
Further, determining when a migrant has arrived at his or her destination
and is no longer in furtherance of an illegal entry can involve making
judgments about the length of time a decedent was in the United States at
the time of death. In most cases of border-crossing deaths, when decedents
are found on known border-crossing trails or the deaths were reported by
other migrants attempting illegal entry, such determinations can be made
with some degree of certainty. However, in other circumstances, the
determination about how long a migrant had been in the United States may
be more difficult. For example, Border Patrol officials reported cases of
migrants who worked on a farm for a period of a few weeks or even a month
after arriving in the United States-to earn funds to complete their
migration-only to die while en route to their final destination. Also, in
cases involving skeletal remains, the determination regarding whether to
record the case as a border-crossing death may be more difficult. Border
Patrol officials and others generally reported that they rarely
encountered ambiguous cases where there was little or no circumstantial
evidence that provided some indication that the decedent was a migrant who
died while trying to cross the border. However, all reported that, in the
absence of being able to confirm the decedent's identity, they must use
their best judgment to make an informed decision about whether the death
should be considered a border-crossing death. Finally, the fact that a
number of bodies may remain undiscovered in the desert also raises doubts
about the accuracy of counts of migrant deaths. While local medical
officials who track border-crossing deaths reported that they do not
believe that there are a large number of undiscovered bodies that would
add significantly to counts of border-crossing deaths, the total number of
bodies that have not been found is ultimately unknown.
Evaluating the Effectiveness of the BSI and Other Border Patrol Efforts to
Reduce Border-Crossing Deaths Presents Measurement Challenges
A number of measurement challenges and data limitations inhibit a
comprehensive evaluation of federal efforts to prevent border-crossing
deaths. In particular, because multiple factors may affect the numbers and
locations of migrant deaths, the effectiveness of the Border Patrol's
efforts to prevent such deaths cannot be measured only by changes in the
number of deaths over time. Factors such as the number of people
attempting to cross the border in any given year, weather conditions, and
the use of smugglers may all affect the number and location of migrant
deaths from one year to the next. Similarly, clear cause and effect
relationships between migrant crossings, the Border Patrol's enforcement
efforts, and prevention initiatives such as the BSI are difficult to
determine. A decline in deaths might incorrectly be associated with BSI
activity. Some migrants may be deterred by the Border Patrol's enforcement
efforts and not attempt to cross at all, while others may attempt to cross
in more dangerous areas in an effort to avoid apprehension. In addition,
because Border Patrol agents typically carry out search and rescue
activities related to the BSI at the same time they carry out enforcement
and apprehension functions, it is difficult to isolate the impact that
prevention efforts may have had on the number of deaths.
A Number of Factors Would Need to Be Considered in Order to Assess Cause
and Effect Relationships between Migrant Crossings, Border Enforcement,
the BSI, and Related Efforts
Because multiple factors beyond the efforts of the BSI may potentially
affect the number of border-crossing deaths in any given year, the
influence of each would need to be taken into account and measured in
relation to the number of migrant deaths in order to accurately assess the
impact of the BSI. Measuring the effectiveness of the BSI in reducing
border-crossing deaths would require a comparison of changes in the number
of migrant deaths with changes in other causal factors-such as the Border
Patrol's enforcement efforts, the number of migrants attempting to cross
the border illegally, and weather conditions, as well as changes in how
and where the BSI is implemented over time. Without correcting for these
factors, cause and effect relationships are difficult to determine. For
example, changes in the Border Patrol's enforcement efforts might lead to
shifts in the locations where migrants attempt to cross. If migrants
attempt to cross in more dangerous areas of the desert in order to avoid
detection, this may lead to an increase in the number of deaths. In this
scenario, the BSI may in fact have prevented deaths through its search and
rescue operations, even though the number of deaths rose as a result of
more migrants crossing in the harsh desert terrain. Alternatively,
increased enforcement efforts may result in migrants being apprehended
before they are in danger or in need of rescue. Similarly, a number of
factors may also affect the number of migrants that attempt to cross the
border. For example, the dynamics of how many people attempt
to cross the border each year may be driven by the relative strength of
the
U.S. labor market in relation to the Mexican labor market. In addition,
the number of migrants that make repeated attempts to cross the border
until they are successful may also change over time. Previous research
suggests that increased enforcement and harsh conditions have made
crossing the border more difficult; consequently, many migrants now pay
smugglers to help them cross.20 The increased difficulty and expense in
crossing may also result in fewer migrants making repeated attempts to
cross the border. Additionally, those who succeed in crossing may choose
to stay permanently in the United States rather than crossing back and
forth for seasonal employment as was the case in years past.
The Border Patrol Does Not Maintain Detailed Data on BSI Operations
If detailed data were available on the extent of the BSI's efforts by
sector, it would be possible to more clearly isolate the program's effects
on trends in deaths, while controlling for other factors that may affect
deaths such as increased enforcement efforts or weather fluctuations.
However, the Border Patrol does not maintain detailed data on where the
BSI was used over time that would be needed to conduct such an evaluation.
Specifically, the Border Patrol does not maintain historical data on the
number of hours agents dedicated exclusively to BSI activities or
historical data on apprehensions made by those agents who were operating
in their search and rescue capacity at the time of apprehension. These
data would provide necessary information about where the BSI was used over
time and allow for more precise measurements of the BSI's implementation
across sectors. Because the Border Patrol's primary function is
enforcement, agents typically carry out search and rescue operations
simultaneously with ongoing enforcement activities. As a result, the
extent to which the Border Patrol can isolate and record the number of
line hours and resources dedicated exclusively to BSI-related activities
is limited.
20
Roberto Corando and Pia M. Orrenius, "The Effect of Illegal Immigration
and Border Enforcement on Border Crime Rates," Research Department,
Federal Reserve Bank of Dallas, 2003.
Page 29 GAO-06-770 Border-Crossing Deaths
The Impact of Additional Border Patrol Programs in Reducing Migrant Deaths
Has Not Been Demonstrated
Border Patrol has claimed that the Interior Repatriation Program (IRP)
resulted in a decrease in migrant deaths and that the decrease in deaths
was due, in part, to a lower recidivism rate among program participants
when compared with those migrants who did not participate in the
program.21 Border Patrol's claims that the IRP contributed to reductions
in deaths were based upon a decline in the number of exposure deaths
recorded in the BSI data between 2003 and 2004. However, this simple
correlation does not constitute sufficient evidence of a causal effect of
the IRP on deaths. First, because participation in the program is
voluntary, it is not possible to determine the program's impact on
recidivism rates and deaths with certainty. Those migrants who choose to
be repatriated to their hometowns in the interior of Mexico may be less
motivated to attempt reentry than those who elect not to participate in
the program, instead choosing to be returned to an entry point along the
border. These migrants may opt out of the program specifically because
they intend to try to cross the border again in the hopes of avoiding
detection on their next attempt. Further, in the second year of the IRP,
the number of deaths increased. If changes in the number of deaths were
again used as the only indication of the program's effectiveness, the
implication could be that the IRP caused a corresponding increase in
deaths between 2004 and 2005. However, as we previously discussed,
multiple factors in addition to the Border Patrol's efforts may affect the
number of deaths in any given year. For example, increased temperatures in
the summer of 2005 may have contributed to an increase in deaths when
compared with the number of deaths recorded for the same time frame in
2004.
A recent House of Representatives Appropriations Committee report suggests
that the Arizona Border Control Initiative (ABCI) was responsible for 27
fewer deaths in the Tucson Sector between March 16, 2004, and September
30, 2004-a 26-percent reduction in such deaths when compared with the same
location and time frame in 2003 prior to the ABCI's implementation.22
However, as we previously discussed, a number of other factors such as
changes in desert temperatures may also affect the number of deaths from
one year to the next. Like the Border Patrol's conclusions about the IRP,
measuring changes in the number of deaths between 2004 and 2005, without
considering other factors, could imply that the program resulted in an
increase in deaths in 2005. Border Patrol
21
U.S. Customs and Border Protection, Interior Repatriation Program 2005
After Action Report, (Washington, D.C.: Nov. 14, 2005).
22
H.R. Rep. No. 109-079, at 29 (2005).
Page 30 GAO-06-770 Border-Crossing Deaths
officials acknowledged that attributing reductions in exposure deaths to
the ABCI and IRP in 2004 was an overly simplistic correlation and that
many factors in addition to enforcement operations may contribute to the
number of deaths in any given year. Officials pointed to the fact that, in
2005, BORSTAR patrols began targeting illegal immigration corridors that
were experiencing high death rates. They reported that one result of
BORSTAR's operations was that rescues of migrants in distress
significantly increased. However, officials also reported that, because
BORSTAR agents were operating in high-risk areas, they may have discovered
more bodies in the course of their patrols, also contributing to an
increase in Border Patrol's total counts of deaths. Additionally, Border
Patrol officials recognized that their data collection methodologies may
also affect conclusions about the cause and effect relationships between
their efforts and migrant deaths. Officials stated that, because they
improved their methodology for collecting data on deaths starting in 2005,
deaths recorded by local coroners that were not routinely included in
their 2004 counts may have also contributed to an increase in the number
of deaths they reported for the Tucson Sector in 2005.
Conclusions
Although the BSI data have some limitations and may undercount the exact
number of border-crossing deaths, the overall trends shown in the data are
corroborated by trends in both the NCHS data as well as the statelevel
vital registry data reported by CIR. The consistency in trends identified
in all three sources of data, as well as our assessment of the BSI
methodology, indicates that the BSI data can be used to provide valuable
information on trends in the numbers, locations, causes, and
characteristics of migrant border-crossing deaths over time. These trends
are particularly important for better understanding the scale of the
problem of migrant deaths and can provide useful information for making
key resource allocation decisions.
Although our analysis of the BSI data shows trends in border-crossing
deaths that are consistent with trends derived from other, independent
sources of data, we also note that not all BSI sector coordinators
consistently implemented the BSI methodology, and these differences can
contribute to incomplete counts of deaths. Some sectors have only informal
and infrequent communication with local authorities, while others have
regularly scheduled contacts with local medical examiners or coroners
about migrant deaths that may have occurred in the sector. Because both
the NCHS and BSI data indicate that the problem of migrant border-crossing
deaths has been growing in recent years, it is important to continue to
improve the available data about these deaths by refining
methods for tracking and recording deaths, including procedures for
communicating with local authorities in order to share information about
all potential cases of border-crossing deaths that occur within the BSI
target zone. The inconsistencies in the implementation of the BSI
methodology highlight opportunities to improve the quality of the Border
Patrol's data on border-crossing deaths. Although there have been
relatively few deaths in the two sectors in which BSI coordinators use
informal methods to contact local authorities, these trends have the
potential to change. If patterns of undocumented migration were to shift,
as occurred in the Tucson Sector between 1998 and 2005, these informal
methods for contacting local officials could result in larger numbers of
unreported deaths. Similarly, since BSI sector coordinators currently have
the latitude to determine how they approach communication with local
officials, personnel changes could also result in changes in how each
sector implements the BSI methodology from one year to the next and
consequently affect counts of deaths.
Finally, the Border Patrol and others should be cautious about believing
assertions about the effectiveness of its prevention efforts, given the
difficulties involved in measuring the effects of such efforts. Claims
about cause and effect relationships are limited by the fact that multiple
factors affect the number of migrant border-crossing deaths from one year
to the next. While we recognize that the Border Patrol's ability to
measure BSI activities separately from ongoing enforcement functions may
be limited, unless explicit controls are introduced to take into account
the effects of these factors, the effectiveness of prevention efforts
cannot be demonstrated.
Recommendations for Executive Action
In order to improve the consistency across Border Patrol sectors in the
implementation of the BSI methodology and the completeness of data on
deaths in any given year, we recommend that the Commissioner of Customs
and Border Protection take steps to ensure that BSI sector coordinators
follow a consistent protocol for collecting and recording information
about border-crossing deaths and that all coordinators follow established
procedures for maintaining and documenting regular contacts with local
authorities to obtain timely information about all bordercrossing deaths
within the BSI target zone.
In order to better demonstrate the effectiveness of the Border Patrol's
efforts to reduce migrant deaths, we recommend that the Commissioner of
Customs and Border Protection assess the feasibility and
cost-effectiveness of using multivariate statistical approaches to enhance
estimates of impacts of the initiatives.
As agreed with your office, unless you publicly announce the contents of
this report earlier, we plan no further distribution of it until 30 days
from the date of the report. At that time, we will then provide copies of
the report to other interested Congressional parties, the Secretary of
Homeland Security, the Secretary of Health and Human Services, the
Secretary of State, and the Assistant Attorney General for Administration
for the Department of Justice, and will make copies available to others
upon request. In addition, the report will be available at no charge on
GAO's Web site at http://www.gao.gov.
If you or your staff have any questions about this report, please contact
me at (202) 512-2758 or [email protected]. Contact points for our Offices
of Congressional Relations and Public Affairs may be found on the last
page of this report. GAO staff who made key contributions to this report
are listed in appendix VI.
Sincerely yours,
Laurie E. Ekstrand
Director, Homeland Security and Justice
Appendix I: Objectives, Scope, and Methodology
This appendix describes our scope and methodology used in responding to
the three objectives addressed in this report: (1) How do the Border
Patrol's data on trends in the numbers, locations, causes, and
characteristics of border-crossing deaths compare to other sources of data
on these types of deaths? (2) What differences, if any, are there in how
the Border Patrol has implemented the BSI methodology across its sectors?
(3) To what extent do existing data allow for an evaluation of the
effectiveness of the BSI and other Border Patrol efforts to prevent
bordercrossing deaths?
Overview of Our Approach and Methodology
To address our objectives, we obtained and analyzed data for the years
1990 through 2005 from the two sources of federal data on border-crossing
deaths-BSI data from the Border Safety Initiative Tracking System (BSITS)
and mortality data collected by the National Center for Health Statistics
(NCHS) as part of the national vital statistics system. We analyzed data
on border-crossing deaths occurring in the United States within the Border
Patrol's identified BSI target zone-45 counties within 9 Border Patrol
sectors on or near the southwest border with Mexico. Prior to analyzing
the data, we assessed the reliability of each data source and found the
data to be sufficiently reliable for the purposes of our report. We
analyzed both sets of data in order to arrive at several estimates of the
number of border-crossing deaths that have occurred annually from 1990 to
2005 and to draw conclusions about the strengths and weaknesses of each
estimate. To understand what each of the federal sources of data reveals
about the trends associated with the numbers, locations, causes, and
characteristics of deaths along the border, we compared each of the two
datasets over time. We examined common trends that were reflected in both
datasets including increases or decreases in the total numbers of deaths,
changes in the locations of deaths, and demographics of decedents in order
to draw conclusions about overall patterns that may have occurred over
time. In addition, we compared trends in each of the two datasets to data
generated by Karl Eschbach and his colleagues at the University of
Houston's Center for Immigration Research (CIR) who used state-level vital
registry data to generate estimates of border-crossing deaths between 1985
and 1998. To understand how deaths among migrants compare to deaths in the
general U.S. population living within the BSI target zone, we compared
each group's share of the causes of death most commonly associated with
border-crossing. Finally, to determine the extent to which existing data
allow for an evaluation of the BSI and other federal efforts to prevent
deaths, we interviewed Border Patrol officials about any established
performance measures and reviewed available information from the Border
Patrol on program outputs and outcomes, including the extent to which the
Border Patrol collects information about the resources dedicated to the
BSI such as the number of agent hours spent on BSI-related activities or
the time agents dedicate to search and rescue operations. We also reviewed
previous efforts to evaluate the effectiveness of the BSI and related
federal efforts to reduce deaths.
We conducted our work between August 2005 and June 2006 in accordance with
generally accepted government auditing standards.
Methods to Determine the Reliability of Sources of Data on
Border-Crossing Deaths
We assessed the reliability of BSI and NCHS data and reviewed the
methods used by CIR for identifying cases of border-crossing deaths in the
state vital registry data.
BSI Data
BSITS is a client-server database that serves as a central repository for
collecting, managing, and disseminating migrant incident data in support
of the BSI including the volume and types of rescues and the number and
types of migrant deaths that occur in each of the nine Southwest Border
Patrol sectors. Specifically, BSITS records the number of deaths and
rescues, followed by type, disposition, location (through GPS
coordinates), and information on the subject or victim. In order to ensure
data integrity, BSITS tracks record creation at the sector and user level.
The BSI does not allow records created outside the user's sector to be
modified in BSITS. The system is monitored by a system security
administrator who monitors all user login and usage in order to maintain a
security audit trail. Access permissions to the system are managed by the
system security administrator through a security management tool, and
users may only log into the system using a secure user ID and password,
which is stored in encrypted binary format. Additionally, BSITS is subject
to a number of requirements that have been established for all sensitive
DHS automated data processing systems: it is required to develop internal
security procedures to restrict access of critical data items to only
those access types required by users; to develop audit procedures to meet
control, reporting, and retention period requirements for operational and
management reports; to allow for application audit trails to dynamically
audit retrieval access to designated critical data; to use standard tables
for requesting or validating data fields; to verify processes for
additions, deletions, or upgrades of critical data; and to be able to
identify all audit
information by user identification, network terminal identification, date,
time, and data accessed or changed.
The Border Patrol provided us an electronic spreadsheet consisting of one
record, or entry, per incident in the BSITS database for all incidents,
including both rescues and deaths, recorded in the system from the
program's inception in 1998 through December 21, 2005. In order to protect
the confidentiality of the information, the Border Patrol omitted names
from the data. In order to accurately interpret the data, we reviewed
definition tables provided by Border Patrol for each of the variables in
the database, system administration manuals, and a copy of the query used
to produce the data for our request. After completing preliminary analysis
of the data, we asked the Border Patrol to confirm the number of subjects
on which data was provided, to clarify the meaning and values of several
key fields in the database, and to provide additional information about
any missing or out of range values. To further assess the reliability of
the BSI data, we reviewed the written BSI methodology for tracking and
recording deaths for logic and consistency and interviewed Border Patrol
officials in Washington, D.C., as well as each of the nine BSI sector
coordinators in the field who have responsibility for implementing the
methodology and inputting data into BSITS. To determine the extent to
which the methodology has been implemented consistently across sectors and
over time, we asked officials about established methodologies for tracking
and recording deaths in BSITS, any changes to those methodologies that may
have occurred over time, and any methods Border Patrol officials have used
at both the national and local level to assess whether the BSI methodology
has been implemented fully and consistently across sectors.
NCHS Data
NCHS collects and disseminates information on national vital statistics
through the National Vital Statistics System. The data are collected
through contracts between NCHS and vital registration systems operated in
the various jurisdictions responsible for the registration of vital events
including births, deaths, marriages, divorces, and fetal deaths. The
authority for the registration of these events resides individually with
each of the 50 states, 2 cities (Washington, D.C., and New York, N.Y.) and
5 territories (Puerto Rico, the Virgin Islands, Guam, American Samoa, and
the Commonwealth of the Northern Mariana Islands). The death certificate
is the source for state and national mortality statistics, and NCHS
provides standard forms for the collection of the data and model
procedures to ensure the uniform registration of deaths. NCHS also
produces training and instructional material as well as an automated
mortality medical data system for coding and classifying cause of death
information from death certificates. The NCHS data include records of all
death certificates filed in the United States regardless of the decedent's
country of origin. In order to assure the objectivity of its statistical
and analytic information products, i.e., that they are accurate, reliable,
and unbiased, NCHS obtains these data through accepted statistical theory
and practice. NCHS statistical and analytic information products are
derived using generally acceptable statistical practices and
methodologies, which enable responsible statisticians and analysts outside
NCHS to replicate the NCHS statistical methods and obtain results
consistent with those obtained by NCHS. NCHS assures the security of its
statistical and analytic information products through the enforcement of
rigorous controls that protect against unauthorized access to the data,
revision or corruption of the data, or unauthorized use of the data. Some
of the major controls used at NCHS include access control, user
authentication, encryption, access monitoring, provision of unalterable
electronic content, and audit trails. Dissemination of data also follows
generally recognized guidelines in terms of defining acceptable standards
regarding minimum response rates, maximum standard errors, cell size
suppression, quality of coding, and other processing operations. NCHS also
maintains staff expertise in areas such as concept development, survey
planning and design (including questionnaire development and testing),
data collection, data processing and editing, data analysis, evaluation
procedures, and methods of dissemination.
We based our data request to NCHS on several key fields in the death
certificate including residence, birthplace, and cause of death in order
to identify likely cases of border-crossing deaths. The CDC Medical
Examiners and Coroner Handbook on Death Registration provides detailed
instructions on the registration of deaths and guidance on completing the
U.S. Standard Certificate of Death. According to the handbook, the
residence of a decedent (state, county, city, and street address) is the
place where the decedent's household is located, the place where the
decedent actually resided, or where the decedent lived and slept most of
the time. If the decedent was not a resident of the United States, the
country of residence should be entered into the residence field of the
death certificate. If the decedent's residence is not known, "unknown" is
entered into the residence field. The guidance also specifies that, for
decedents who were not born in the United States, the country of birth
should be entered into the death certificate, regardless of whether the
person was a U.S. citizen at the time of death. CDC's specifications
further state that the underlying cause of death listed on the death
certificate should be the disease or injury that initiated the chain of
events that led directly and inevitably to death. The underlying cause of
death is defined as "the disease or injury which initiated the train of
morbid events leading directly to death, or the circumstances of the
accident or violence which produced the fatal injury." Reported causes of
death are then translated into codes through a classification structure
outlined in the International Classification of Diseases (ICD) developed
by the World Health Organization. The ICD is used to classify diseases and
other health problems recorded on many types of health and vital records
including death certificates and hospital records. In 1999, a revision of
the ICD was implemented. The International Statistical Classification of
Diseases and Related Health Problems, Tenth Revision (ICD-10), established
revised codes for classifying mortality data and revised rules for
selecting the underlying cause of death. ICD-10 replaced classification
codes and rules outlined in the previous version of the manual, the
International Classification of Diseases, Ninth Revision (ICD-9). The
codes outlined in the 9th revision (ICD-9) apply to all deaths registered
between 1979 and 1998, while the 10th revision (ICD-10) applies to all
deaths from 1999 to the present.
In order to identify migrant deaths recorded in the NCHS main mortality
file-which contains records of all deaths occurring in the United States-
we requested that NCHS provide us with aggregate, county-level data on
migrant border-crossing deaths by applying a set of specifications to the
data in the main mortality file.1 Our specifications included the
following:
(1) a death must have occurred within 1 of the 45 counties in the BSI
target zone; (2) the death must have occurred in years beginning with 1990
and going through 2003, the most recent year for which NCHS data were
available at the time we did our work; and (3) deaths must be limited to
decedents who were foreign born, had a place of residence outside the
United States at the time of death, and died from one of the causes of
death that we associated with border-crossing deaths. We provided NCHS a
list of causes of death from the codes contained in the ICD codes- which,
as described above, are used to classify the underlying cause of death
reported on the death certificate by public health officials such as
medical examiners and county coroners-and asked that NCHS officials select
those cases that matched one of the underlying causes of death on our
list. By requesting data over the period from 1990 to 2003, we identified
both ICD-9 and ICD-10 codes. We selected cause of death codes
NCHS mortality data provided by Robert Anderson, Chief, Mortality
Statistics Branch, Division of Vital Statistics, and Jiaquan Xu, NCHS/CDC.
Page 38 GAO-06-770 Border-Crossing Deaths
that were associated with migrant border-crossing deaths used in the CIR
studies, the causes of migrant deaths identified by the Border Patrol, as
well as causes most commonly used by county medical examiners, advocacy
groups, and academic researchers. These include dehydration, heat
exposure, drowning, cold exposure, homicide, and traffic accidents among
others. Our data specifications also requested that NCHS provide us with
separate counts of decedents with unknown places of birth. NCHS provided
separate datasets for each year. The datasets also contained counts of
migrant deaths by age group and gender. After receiving the data from
NCHS, we reviewed the programming code as well as the statistical output
in order to verify that the results matched our initial specifications.
Because the place of residence listed on the death certificate is not
necessarily the same as the decedent's home state, voting residence,
mailing residence, or legal residence, our counts of border-crossing
deaths may include some decedents who were either legal visitors or legal
residents of the United States but who were residing in another country
when they legally crossed the border and subsequently died. Additionally,
NCHS officials reported that if a body is discovered and the body is
unable to be identified, the person may be assumed to be a U.S. resident.
As a result, our counts may have excluded unidentified migrants who were
presumed to be U.S. residents by public health officials completing the
death certificate. Similarly, we requested that NCHS only provide data on
those cases where the underlying cause of death was a death commonly
associated with border-crossing. Focusing on the underlying cause of death
could result in undercounts of border-crossing deaths; cases could be
missed if the commonly associated causes are not reported when appropriate
or if they are reported incorrectly out of sequence. For example, heat
exhaustion may precipitate a heart attack. If heat exhaustion is not
reported at all or if it is not reported correctly as the cause of the
heart attack, then the heart attack would be coded as the underlying
cause, and the case would be excluded because the NCHS data did not
include heart attacks in the list of commonly associated causes of
border-crossing deaths. Alternatively, the NCHS data could also represent
an overcount of deaths if cause of death categories were defined too
broadly and resulted in the inclusion of deaths that were not directly
related to border-crossing.
In order to determine the reliability of the NCHS data for identifying
trends in deaths, we interviewed NCHS officials responsible for
maintaining vital registry mortality data and reviewed published NCHS
guidance on the completion of death certificates. We conducted interviews
with NCHS researchers, academic experts, and county medical examiners
familiar with the vital registry data about the data's strengths and
limitations for accurately capturing data on border-crossing deaths. We
also reviewed NCHS documentation about the methods for collecting and
analyzing death certificate data in preparing the main mortality files.
CIR Data
In order to understand the methods and data compiled by CIR, we
conducted interviews with Karl Eschbach, the lead author of the studies,2
about his methods for collecting and analyzing the data and also conducted
a GAO internal review of CIR methods.
Methods Used to Identify Trends in Federal Data on the Numbers, Locations,
Causes, and Characteristics of Border-Crossing Deaths
We analyzed specific data elements in the BSI data that were relevant to
our analysis of border-crossing deaths. These included the number of
deaths, the types or causes of death-such as exposure to heat/cold, motor
vehicle accidents, drowning, and others-the location of deaths including
the county, sector, and GPS coordinates, and demographic information on
the decedent including age, gender, and country of origin. We imported the
data from the spreadsheet provided by the Border Patrol into a statistical
software package and analyzed counts of BSI-related deaths by year,
sector, and cause of death for fiscal years 1998 through 2005. Based on
discussions with Border Patrol officials and the criteria outlined in
Border Patrol's 2005 BSI Methodology Manual, we identified border-crossing
deaths as those deaths occurring within the 45 counties in the BSI target
zone and only included those entries designated by Border Patrol as
migrants who were in furtherance of an illegal entry at the time of death.
We also analyzed counts for characteristics of decedents including gender
and age.
Our analysis of the BSI data is based only on those deaths included in
BSITS as of December 21, 2005. We selected cases from fiscal year 1998
through fiscal year 2005 in which border-crossing deaths were recorded as
having occurred within one of the 45 counties in the BSI target zone while
the decedent was in the furtherance of an illegal entry into the United
States. Our methodology is consistent with the BSI definition of a
bordercrossing death, but it differs from the methodology that Border
Patrol uses to calculate the total number of border-crossing deaths that
occur each year. According to Border Patrol officials, the Border Patrol
generates its reported annual death totals by selecting those cases
recorded in the BSITS database that occurred within any one of the Border
Patrol stations
2
Eschbach, et al., 2001 and Eschbach, et al., 2003.
located within the BSI target zone or outside of the target zone if Border
Patrol was directly involved in the incident. In our analysis of the BSI
data, we only included deaths occurring within one of the 45 BSI counties
and did not select deaths that may have occurred outside of the target
zone. As a result, our total counts may not match the total numbers
reported by the Border Patrol. Additionally, our sector-level counts of
border-crossing deaths may also differ from Border Patrol's. Border Patrol
classifies deaths into sectors based on the Border Patrol station that
recorded the death. Using the criteria outlined in the 2005 BSI
Methodology Manual, we instead used data regarding the county in which the
death occurred to classify deaths into sectors. Furthermore, 3 of the 45
counties in the BSI target zone straddle the dividing line between two
different Border Patrol sectors. In these cases, our analysis may have
identified deaths in these counties as occurring in one sector, while the
Border Patrol's reports may have counted the deaths as occurring in
another sector. These differences in methods of classification primarily
affect reported totals for the El Centro and Yuma sectors.
Methods Used to Compare Border-Crossing Deaths to Deaths in the General
Population
To understand how the distributions of causes of migrant border-crossing
deaths compare to the general population, we analyzed relevant BSI and
NCHS data on the numbers and causes of death. From NCHS we requested
aggregate, county-level datasets for the years from 1990 through 2003 of
the number of U.S. residents who died each year in the 45 counties in the
BSI target zone and the numbers who died from the causes of death we used
to identify border-crossing deaths. We followed procedures similar to
those we followed in requesting and obtaining the NCHS data on migrant
deaths. We also compared counts of U.S. resident deaths by year, sector,
and county, including the total numbers and causes of death with migrant
border-crossing deaths between 1990 and 2003.
Assessing Change in Risk Associated with Attempted Illegal Entries
To assess whether the apparent risk associated with migrant bordercrossing
deaths has changed over time, we compared data on bordercrossing deaths to
data on the estimated number of illegal entries reported in a published
study by Jeffrey Passel at the Pew Hispanic Center3 as well as to data on
the number of apprehensions recorded by Border Patrol. Passel's estimates
are based upon the residual methodology. We used data on apprehensions
that the Border Patrol provided us. We calculated the percentage change
over the period from 1998 through 2004 in the
3
Jeffrey S. Passel and Roberto Suro, "Rise, Peak, and Decline: Trends in
U.S. Immigration 1992-2004," Pew Hispanic Center (Washington, D.C.: Sept.
27, 2005).
Page 41 GAO-06-770 Border-Crossing Deaths
estimated number of undocumented entries, the number of apprehensions, and
the number of border-crossing deaths, and we compared these percentage
changes to determine if the change in the number of deaths over this
period exceeded the change in the estimated number of undocumented entries
and the number of apprehensions (see table 2).
Table 2: Estimated Undocumented Entries, Apprehensions, and Deaths
Estimated number of undocumented entries
Number of apprehensions
Year Total Mexico along the southwest Number of BSI deaths
border
1998 668,000 507,000 1,516,680 254
1999 656,000 496,000 1,537,000 241
2000 667,000 530,000 1,643,679 372
2001 549,000 437,000 1,235,717 328
2002 450,000 378,000 929,809 322
2003 451,000 369,000 905,065 334
2004 562,000 459,000 1,139,282 328
Percent change
from 1998 to 2004 -15.9% -9.5% -24.9% 29.1%
Review of Models Used to Estimate the Number of Migrants Attempting to
Cross the Border
Sources: Passel and Suro, 2005; U.S. Border Patrol; and GAO analysis of BSI
data.
Because data are not available on the actual number of migrants that
illegally attempt to cross the border in any given year, we used estimates
of the number of border-crossers or undocumented migrants that enter the
United States each year. We previously reported on some of the data
limitations involved in estimating the illegal immigrant population as
well as the strengths and weaknesses of the available methods for
estimating the flow of illegal migrants across the border.4 We reviewed a
number of models that have been developed in recent years by researchers
and academic experts working in the arena of immigration issues. We
conducted an analysis of each model and assessed the methods used by each
in order to draw a conclusion about the most reliable estimates of illegal
entries.
Residual Method
Robert Warren and Jeffrey Passel employ a method for estimating the number
of unauthorized migrants using both data from the decennial
4
GAO/PEMD-93-25.
Census and counts from alternate government sources, such as DHS.5 This
method counts the number of foreign born individuals in the United States,
as enumerated in the Census or the Current Population Survey (CPS), and
then subtracts the number who have become naturalized or who are legal
resident aliens,6 which was obtained from the alternate government source.
The difference should be the number of undocumented aliens. Because this
method involves subtraction, it is sometimes called the "residual method."
Table 3: The Residual Method for Estimating the Number of Unauthorized Migrants
Estimated number of Foreign born undocumented = population aliens counted
in the counted in the census census Estimated Estimated
- naturalized U.S. -legally citizens in the resident aliens United States
in the United
States
Source: Warren and Passel, 1987.
Using a method similar to this one, Passel estimated that there were
10.3 million unauthorized migrants in the United States in 2004. Using
annual applications of this method, he estimated that between 400,000 and
700,000 unauthorized migrants have entered the United States each year
since 1992.
A drawback to using this methodology for measuring the number of
unauthorized migrants at risk for border-crossing deaths is that Census
Bureau data, such as the CPS, only count migrants who have been in the
United States for a sufficient amount of time for government census takers
to locate them. Migrants who only come to the United States for a short
period of time and then return to their home country would be less likely
to be included in this count. Further, this methodology cannot be used to
measure different rates of crossing by sector since the migrants may live
in different areas from where they crossed the border. Ultimately, this
method would not only count those individuals who crossed the border
illegally, but also those individuals whose status changed from authorized
to unauthorized, due to a visa expiring, for example.
5
Robert Warren and Jeffrey S. Passel, "A Count of the Uncountable:
Estimates of Undocumented Aliens Counted in the 1980 United States
Census," Demography, Vol. 24, No. 3, August 1987.
6
Legal resident aliens include permanent resident aliens, students,
refugees, and other aliens who would be considered residents by U.S.
census rules.
Page 43 GAO-06-770 Border-Crossing Deaths
Apprehensions Data
An alternate method for estimating the total number of illegal border
crossings is to calculate entries based on the number of apprehensions
recorded by the Border Patrol. From 1994 through 2004, Border Patrol
records indicate that between 0.9 and 1.7 million migrants were
apprehended in the nine southwest Border Patrol sectors each year, peaking
in 2000. However, apprehensions are partially determined by the level of
Border Patrol enforcement activity. Therefore, even if the level of
migration remained the same, the number of apprehensions might fluctuate
if the level of enforcement changes. More specifically, apprehensions are
not a direct measure of successful undocumented migration, but rather they
are an indication of unsuccessful undocumented migration.
Unlike the residual method, because the Border Patrol maintains records of
apprehensions by sector, this method can be used to estimate entries by
sector. Border Patrol data indicate that, from 1992 to the present, there
was a large shift in apprehensions from the San Diego Sector to the Tucson
Sector.
In addition, the number of apprehensions is not the same as the number of
apprehended migrants, since many migrants attempt to cross the border a
number of times until they are able to cross successfully. Katharine M.
Donato reports survey evidence that shows that many migrants will continue
to attempt to cross the border until they are able to get through
undetected.7
Repeated Trials
Another method for estimating undocumented migration uses the number of
people who have been apprehended previously to translate apprehensions
into an estimate of the number of undocumented migrants crossing into the
country. A version of this method is employed by Thomas
J. Espenshade in his 1995 study examining the use of INS data to measure
the flow of undocumented migration.8 Espenshade shows that the ratio of
apprehensions and undocumented flow is equal to the odds of being
apprehended on any given attempt to enter the United States illegally. It
follows then that the flow of undocumented migrants can be calculated by
7
Katharine M. Donato, et al., "Stemming the Tide? Assessing the Deterrent
Effects of the Immigration and Control Act," Demography, Vol. 29, No. 2,
May 1992.
8
Thomas J. Espenshade, "Using INS Border Apprehension Data to Measure the
Flow of Undocumented Migrants Crossing the U.S.-Mexico Frontier,"
International Migration Review, Vol. 29, No. 2. 1995.
Page 44 GAO-06-770 Border-Crossing Deaths
dividing the number of apprehensions by those odds. Espenshade estimates
that the estimated gross volume of undocumented migration generally
exceeded the level of apprehensions by 2.2 in the period between 1977 and
1988. While this factor varies over time, Espenshade concludes that the
two series track each other well, as the linear correlation between them
is 0.90.
However, there are some questions about using Espenshade's model to
estimate the current number of illegal crossings. For one, the specific
factor may be different today; Espenshade's figures are based on
calculations over an 11-year period, beginning almost 30 years ago. As
noted previously, the geographic pattern of migration was much different
then, with a larger number of crossings occurring in the San Diego area,
whereas today a more significant number of crossings occur in the desert
area of Arizona. Moreover, Gordon Hanson and Antonio Spilimbergo have
empirically demonstrated that as the level of border security increases, a
greater number of unauthorized migrants will be apprehended.9 Either of
these factors-a differential pattern of crossing or an increased level of
Border Patrol enforcement-may affect the ability of the Border Patrol to
apprehend migrants, thus affecting the extent to which Espenshade's
estimate of 2.2 crossings per apprehension can be accurately applied to
current circumstances.
In addition, a key assumption of Espenshade's model is that migrants will
attempt to enter repeatedly until they are successful, even if all entries
were attempted within a single month. However, the plausibility of this
assumption is unclear; for example, it may not be reasonable to assume
that a migrant will attempt to cross the border as many as 7 times in a
given month. Additionally, there are a number of other factors that may
make the assumption even less plausible today than it was in the period of
Espenshade's study. Border Patrol apprehension data indicate that
increasing numbers of migrants are attempting to cross in the Tucson
Sector. However, due to high temperatures and rugged terrain, the desert
is often more difficult for migrants to navigate than urban areas. As a
result, increasing numbers of migrants hire smugglers, or "coyotes," to
help them cross. This is a large expense, and it is not clear that the
coyotes refund the money if the crossing is not successful. In addition,
the Border
Gordon Hansen and Antonio Spilimbergo, "Illegal Immigration, Border
Enforcement, and Relative Wages: Evidence from Apprehensions at the
U.S.-Mexico Border," The American Economic Review, December 1999.
Page 45 GAO-06-770 Border-Crossing Deaths
Patrol has started returning migrants to the interior of Mexico through
the IRP in order to deter repeat attempts. Given the amount of time it
might take a migrant to travel from the interior of the country back to
the border, it seems likely that a migrant would be able to make fewer
attempted crossings within a single month.
Methods to Determine the Extent to Which the BSI Can Be Evaluated
In order to determine the extent to which existing data allow for an
evaluation of the effectiveness of the BSI and related Border Patrol
efforts, we interviewed Border Patrol officials in Washington, D.C., about
how they measure the BSI including any information on established
performance goals and measures. We requested any available information on
BSI resources, personnel, and equipment in order to determine the extent
to which the Border Patrol tracks and records information on resources in
relation to established performance goals and measures. We also reviewed a
number of other federal data sources on the Border Patrol's program goals
and outcome measures including documents published by the Office of
Management and Budget and CBP's annual budget submission. We reviewed and
analyzed available information from the Border Patrol on program outcomes
including a study on the BSI conducted in July 2004 that examined the
efforts of the BSI to reduce the overall number of migrant deaths, the
effectiveness of individual components of the BSI to deter crossings, and
the effect of specially trained BORSTAR units, as well as the Lateral
Repatriation Program, on the number of deaths.
The Border Safety Initiative: Evaluation, Assessment, and Recommendations
In an effort to better measure the impact of the BSI, the Border Patrol
commissioned researchers at Rutgers University to evaluate the efforts of
the program.10 As one of its objectives, the study examined the
effectiveness of specialized BORSTAR agents in reducing migrant deaths
when compared with Border Patrol line agents. BORSTAR agents are often
deployed to high-threat areas or areas more likely to have deaths and
rescues. Rather than attempt to estimate the effect of the BORSTAR agents
on the number of deaths in a sector where they are deployed, the study
estimates the effect of an agent's BORSTAR training on whether an
intervention results in a death or a rescue of a migrant. The researchers
applied a multivariate logistic regression that corrects for the migrant's
10
Ronald V. Clarke and Rob T. Guerette, The Border Safety Initiative:
Evaluation, Assessment and Recommendations for Strategic Action, Phase 1
Report, July 2004.
Page 46 GAO-06-770 Border-Crossing Deaths
age, gender, and the number of accompanying migrants. Using existing data
provided by the Border Patrol, they found that the probability of a death
is 88 percent less when a BORSTAR agent responds, as opposed to a
non-BORSTAR Border Patrol agent.
The study's findings present an argument for BORSTAR's effectiveness. If
BORSTAR agents have training that allows them to better treat injuries, it
follows that more rescued migrants will survive. However, it is unclear
whether findings from this analysis can be used as an evaluation of the
BSI as a whole without additional research. BORSTAR agents are only one
component of the BSI with a total of 164 BORSTAR agents deployed in the 9
sectors along the southwest border as of October 2005. In order to
understand the effectiveness of the program as a whole, it would be
necessary to examine the impact of other components of the program
including the use of rescue beacons, the impact of the media campaign to
discourage migrants from attempting to cross the border illegally, and the
effectiveness of other non-BORSTAR Border Patrol agents that may rescue
migrants in need of assistance.
2005 Report on the Interior Repatriation Program
In 2005, the Border Patrol issued a report on the outcomes of the Interior
Repatriation Program (IRP), an effort initiated as part of the ABCI. The
Border Patrol reports that the IRP was intended to break the ties between
migrants attempting to cross the border and the smuggling organizations
that move people across the border. Program participants are migrants who
are apprehended while attempting to illegally cross the border; the IRP
offers them the option to be voluntarily repatriated to their hometown,
rather than being returned to a land port of entry along the border where
they might be more likely to attempt to cross again. The program claimed a
number of successes including a decrease in the total number of exposure
related deaths between 2003 and 2004 in Arizona, as well as a lower
recidivism rate among program participants. However, exposure related
deaths in the Tucson and Yuma Sectors actually increased between 2004 and
2005. While the Border Patrol claims that the IRP was responsible for
reducing the number of deaths in Arizona between 2003 and 2004, they do
not similarly tie the increase in deaths between 2004 and 2005 to the
program. Rather, Border Patrol officials point out that increased desert
temperatures and improved data collection methods may have contributed to
the increase in recorded deaths. Similarly, they state that increased
numbers of deployed BORSTAR agents may have increased the likelihood that
agents would find deceased migrants in the course of their patrols.
Factors discussed in this report point out that changes in the number of
deaths alone cannot serve as a reliable indicator for the success of the
BSI or the IRP. As the Border Patrol correctly notes, any number of
factors beyond the efforts of the Border Patrol may affect the number of
deaths from one year to the next. Just as the increase in recorded deaths
between 2004 and 2005 may have been affected by any one of a number of
factors including increased temperatures, increased patrols, or improved
data collection, the decline in deaths between 2003 and 2004 may have also
been affected by a number of factors independent of the IRP. Similarly,
the report points to the decreased recidivism rate among program
participants, noting that the reentry rate was lower among program
participants than illegal aliens that were returned to land border ports
of entry. However, currently participation in the IRP is voluntary, and
those migrants who elect to participate may be less likely to attempt to
cross the border again. Conversely, those migrants who intend to continue
to attempt to cross until they are successful may be less likely to
participate in the IRP.
Appendix II: Deaths by Sector
Figure 8: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the San Diego Sector, 1985 through 2005
Number of deaths250
200
150
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 9: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the El Centro Sector, 1985 through 2005
Number of deaths250
200
150
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 10: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Yuma Sector, 1985 through 2005
Number of deaths250
200
150
100
50
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 11: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Tucson Sector, 1985 through 2005
Number of deaths250
200
150
100
50
0
1985 1986 1987 19881989 1990 1991 1992 19931994 1995 1996 1997 19982000
1999 2001 2002 20032004 2005
Year of death
NCHS data
BSI data
CIR findingsSource: GAO analysis of BSI and NCHS data; CIR findings, as
reported in Eschbach, et al., 2001, 24-61.
Figure 12: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the El Paso Sector, 1985 through 2005
Number of deaths250
200
150
100
50
0
198719861985 1988 1989 1990 200220012000199919981997199619951994199319921991 200520042003
Year of
death
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61. NCHS dataBSI dataCIR findings
Figure 13: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Marfa Sector, 1985 through 2005
Number of deaths250
200
150
100
50
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 14: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Del Rio Sector, 1985 through 2005
Number of deaths250
200
150
100
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 15: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Laredo Sector, 1985 through 2005
Number of deaths250
200
150
100
50
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2001 2002 2003 2004 2005
1999
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR
findings, as reported in Eschbach, et al., 2001,
24-61.
Figure 16: Migrant Border-Crossing Deaths in the BSI Target Zone Occurring
within the Rio Grande Valley Sector, 1985 through 2005
Number of deaths250
200
150
100
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year of death
NCHS data
BSI data
CIR findings
Source: GAO analysis of BSI and NCHS data; CIR findings, as
reported in Eschbach, et al., 2001, 24-61.
Appendix III: Causes of Death
Figure 17: Migrant Border-Crossing Deaths, by Cause of Death, CIR
Findings, 1985 through 1998 Number of all deaths200 180 160 140 120 100 80
60 40 20 0
1985 1986 1987 19881989 1990 1991 1992 19931994 1995 1996 1997 1998
Year of death
Motor vehicle accidentsAll environmental causesHomicide Drowning
Pedestrian deaths from vehicular traffic
Source: CIR findings, as reported in Reyes, et al., 2002, 68. Notes:
Number of deaths based on cause of death counts as reported in Reyes, et
al., 2002, 68. CIR findings include data from 55 counties. Environmental
causes include heat-related causes, hypothermia, and other environmental
conditions. See figure 5 for causes of death according to our analysis of
NCHS data.
Figure 18: Migrant Border-Crossing Deaths, by Cause of Death, BSI Data,
1998 through 2005
Number of all deaths
0
1998 1999 2000 2001 2002 2003 2004 2005
Year of
death
All traffic-related fatalities
All exposure, heat and cold
Other
Drowning
Source: GAO analysis of BSI data.
Notes: Other deaths include homicide, suicide, and
Border Patrol shootings. All traffic-related
fatalities include motor vehicle accidents and
pedestrian deaths from vehicular traffic. See figure 5
for
causes of death according to our analysis of NCHS data.
Appendix IV: Causes of Death for U.S. Residents and Migrants within the BSI
Target Zone
Figure 19: Percentage Distribution of Deaths among U.S. Residents and
Migrant Border-Crossers, by Cause of Death, All Years Combined, 1990
through 2003
Cause of death
0 5 10 15 20 253035
Percentage of deaths
Migrant border-crossing deaths
U.S. resident deaths
Source: GAO analysis of NCHS data.
Notes: Our analysis of the NCHS data shows that between 64,000 and 87,100
U.S. residents died annually from any cause of death in the counties in
the BSI target zone over the period from 1990 through 2003. Of these,
nearly 5 percent died from the causes of death that are commonly
associated with border-crossing deaths, such as exposure to heat, traffic
accidents, environmental causes, and homicide.
Appendix V: Comments from the Department of Homeland Security
Appendix VI: GAO Contacts and Staff Acknowledgments
GAO Contact
Laurie E. Ekstrand (202) 512-2758
In addition to the contact named above, William J. Sabol,
Samantha Goodman, Benjamin Bolitzer, Chad M. Gorman, David Alexander, Amy
Bernstein, Frances Cook, Ignacio Yanes, Jerry Seigler, Christopher
Ferencik, and Stephen Rossman made key contributions to this report.
(440450)
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