[Federal Register Volume 72, Number 66 (Friday, April 6, 2007)]
[Notices]
[Pages 17337-17343]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-6467]


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DEPARTMENT OF COMMERCE

Bureau of the Census

[Docket Number 070126022-0723-01]


Census Block Group Program for the 2010 Census--Proposed Criteria

AGENCY: Bureau of the Census, Commerce.

ACTION: Notice of proposed program revisions and request for comments.

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SUMMARY: Block groups are statistical geographic divisions of a census 
tract, defined for the tabulation and dissemination of decennial census 
data. Block groups also will be used to tabulate and publish estimates 
from the American Community Survey (ACS) \1\ after 2010. Each block 
group comprises a reasonably compact and contiguous cluster of census 
blocks; up to nine block groups can be contained within a single census 
tract.
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    \1\ The ACS is conducted in the United States and in Puerto 
Rico. In Puerto Rico, the survey is called the Puerto Rico Community 
Survey. For ease of discussion, throughout this document the term 
ACS is used to represent both the survey that is conducted in the 
United States and in Puerto Rico.
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    Most provisions of the block group criteria for the 2010 Census 
remain unchanged from those used in conjunction with Census 2000. 
However, based on consultation with data users and internal review, the 
Bureau of the Census (Census Bureau) is proposing the following changes 
for the 2010 Census: (1) Increasing the minimum population and housing 
unit counts for block groups; (2) using housing unit counts (as an 
alternative to population counts) in the delineation of block groups; 
(3) applying the same population and housing unit thresholds to all 
types of populated block groups in the United States,\2\ including 
block groups delineated on American Indian reservations and/or off-
reservation trust lands,\3\ the Island Areas,\4\ and encompassing group 
quarters, military installations, and institutions; (4) allowing the 
delineation of block groups for large water bodies with areas of 
approximately 100 square miles or more and special land uses (e.g., 
large airports or public parks) with an official name; and (5) allowing 
for geographic frameworks of tribal block groups (separate from the 
standard block groups defined within counties and standard census 
tracts) to be defined within federally-recognized American Indian 
reservations and/or off-reservation trust lands.
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    \2\ For Census Bureau purposes, the United States includes the 
fifty states and the District of Columbia.
    \3\ The proposed criteria for the tribal statistical areas 
program will be outlined in a separate Federal Register notice. In 
the tribal statistical areas program, federally recognized American 
Indian tribes that have a reservation and/or off-reservation trust 
land may delineate census designated places and, if these areas have 
a population of 2,400 or greater, may delineate tribal tracts and 
tribal block groups for their reservation and off-reservation trust 
land.
    \4\ For Census Bureau purposes, the Island Areas includes 
American Samoa, the Commonwealth of the Northern Mariana Islands, 
Guam, the U.S. Virgin Islands, and the U.S. Minor Outlying Islands. 
The U.S. Minor Outlying Islands is an aggregation of nine U.S. 
territories: Baker Island, Howland Island, Jarvis Island, Johnston 
Atoll, Kingman Reef, Midway Islands, Navassa Island, Palmyra Atoll, 
and Wake Island.
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    In addition to the proposed criteria, this notice includes a 
description of the changes from the criteria used for Census 2000 and a 
list of definitions of key terms used in the criteria.
    The Census Bureau is publishing this notice in the Federal Register 
to request comments from the public and other government agencies. The 
Census Bureau will respond to the comments received as part of the 
publication of final criteria in the Federal Register. After the final 
criteria are published in the Federal Register, the Census Bureau will 
offer designated governments or organizations an opportunity to review 
and, if necessary, suggest updates to the boundaries and attributes of 
the block groups in their geographic area under the Participant 
Statistical Areas Program (PSAP). In addition to block groups, the 
program also encompasses the review and update of census tracts, census 
designated places, and census county divisions.

DATES: Written comments must be submitted on or before July 5, 2007.

ADDRESSES: Please direct all written comments on this proposed program 
to the Director, U.S. Census Bureau, Room 8H001, Mail Stop 0100, 
Washington, DC 20233-0001.

FOR FURTHER INFORMATION CONTACT: Requests for additional information on 
this proposed program should be directed to Michael Ratcliffe, Chief, 
Geographic Standards and Criteria Branch, Geography Division, U.S. 
Census Bureau, via e-mail at [email protected] or telephone at 
301-763-3056.

SUPPLEMENTARY INFORMATION:

I. History of Block Groups

    The Census Bureau first delineated block groups as statistical 
geographic divisions of census tracts for the 1970 Census, comprising 
contiguous combinations of census blocks for data presentation 
purposes. At that time, census block groups only existed in urbanized 
areas in which census blocks were defined. Block groups were defined 
without regard to political and administrative boundaries, with an 
average population of 1,000, and to be approximately equal in area.
    As census block, block group, and census tract data were used 
increasingly by data users, the Census Bureau expanded these programs 
to cover additional geographic areas, while redefining the population 
threshold criteria to more adequately suit data users' needs. The 1990 
Census was the first in which census blocks and block groups were 
defined throughout the entirety of the United States, Puerto Rico, and 
the Island Areas. For Census 2000, as with census tracts, the Census 
Bureau increased the number of geographic areas whose boundaries could 
be used as block group boundaries, and allowed tribal governments of 
federally recognized

[[Page 17338]]

American Indian tribes with a reservation and/or off-reservation trust 
lands to delineate block groups without regard to state and/or county 
boundaries, provided the tribe had a 1990 Census population of at least 
1,000.

II. General Principles and Criteria for Block Groups for the 2010 
Census

A. General Principles

    1. Block groups are statistical geographic divisions of a census 
tract, defined by the Census Bureau in cooperation with local officials 
and organizations, for the tabulation and dissemination of decennial 
census data as well as period estimates of demographic and housing 
characteristics from the ACS.
    2. Because block groups are used to present and analyze sample-
based statistical data, the amount of population or housing units 
within a block group is an important consideration. As a general rule, 
estimates from programs providing sample data, including the ACS, for 
geographic areas with smaller populations are subject to higher 
variances than comparable estimates for areas with larger populations. 
Aiming to create block groups that fall between the minimum and maximum 
thresholds will improve the reliability and availability of data, and 
local governments and planners should consider these factors when 
defining their block groups.
    3. Block groups form the geographic framework within which the 
Census Bureau defines census blocks for use in tabulating and 
presenting decennial census data. Census blocks are numbered within 
block groups.
    4. Geographic areas that are not characterized by a residential 
population, such as parks, large industrial areas, and water bodies, 
and which local participants may wish to separate from populated census 
tracts for analytical or cartographic purposes, or both, may be 
identified as individual block groups.

B. Proposed Changes to the Block Group Criteria for the 2010 Census

    Most provisions of the block group criteria for the 2010 Census 
would remain unchanged from those used in conjunction with Census 2000 
with the following exceptions:
    1. The Census Bureau proposes to increase the minimum population 
and housing unit counts for block groups to 1,200 and 480, 
respectively, to support block group sample data reliability and 
availability and to lower the variance of the sample data. The sample 
size for the ACS is smaller than the sample from the decennial census 
long form of previous censuses. As a general rule, estimates from 
programs providing sample data, including the ACS, for geographic areas 
with smaller populations will be subject to higher variances than 
comparable estimates for areas with larger populations. In addition, 
the Census Bureau's disclosure rules will have the effect of 
restricting the availability and amount of data for areas with small 
populations. Aiming to create block groups that fall between the 
minimum and maximum thresholds will improve the reliability and 
availability of data, and local governments and planners should 
consider these factors when defining their block groups.
    2. Housing unit counts may be used instead of population counts in 
the delineation of block groups. This change seeks to accommodate 
seasonal communities in which residents may not be present on the date 
of the decennial census, but will be present at other times of the year 
and for which data may be reflected in the ACS.
    3. For Census 2000, minimum population thresholds for block groups 
varied. The minimum population threshold for block groups delineated on 
American Indian reservations and off-reservation trust lands was 300. 
This differed from the minimum threshold of 600 people for block groups 
defined elsewhere in the United States, as well as in Puerto Rico and 
the Island Areas. The maximum population for a block group in any of 
these areas was 3,000. In addition, for Census 2000, block groups that 
enclosed an institution, a military installation, or other ``special 
place'' had a minimum population requirement of 300 inhabitants, with 
no optimum or maximum population.
    For the 2010 Census, the same population and housing unit 
thresholds (minimum: 1,200 inhabitants or 480 housing units; maximum: 
3,000 inhabitants or 1,200 housing units) would apply to all types of 
populated block groups, including block groups delineated for American 
Indian reservations and off-reservation trust lands, the Island Areas, 
and encompassing group quarters, military installations, and 
institutions. The Census Bureau proposes this change in order to aid in 
the availability and reliability of data for all block groups and to 
create a single national standard.
    4. The delineation of block groups would be permitted, and 
encouraged, for the following specific types of geographic areas:
    a. Large water bodies with areas of approximately 100 square miles 
or more.
    b. Special land uses (e.g., large airports, public parks, or public 
forests) with an official name.
    A single water body or special land use block group will be 
delineated to be coextensive with, or covering the same territory as, 
the water body or special land use tract in which it is located.
    The Census Bureau would require that block groups delineated to 
encompass large water bodies and special land uses have little or no 
residential population. The Census Bureau recognizes that some special 
land use areas not generally intended for residential population, such 
as parks, may contain some population, such as caretakers or the 
homeless. Our intent is to allow for the delineation of parks and other 
special land use areas as separate block groups and, therefore, will 
accept such areas as block groups even if some residential population 
is present. All such block groups would meet all other block group 
criteria.
    5. A geographic framework of tribal block groups, separate from the 
standard block groups defined within counties, may be defined within 
federally recognized American Indian reservations and/or off-
reservation trust lands, subject to other population, housing, and 
boundary criteria contained in this document. This represents a change 
from the practice for Census 2000. The Census Bureau proposes this 
change to better recognize the unique statistical data needs of 
federally recognized American Indian tribes and their reservation and 
off-reservation trust lands.

C. Block Group Criteria for the 2010 Census

    The criteria proposed herein apply to the United States, including 
federally recognized American Indian reservations and off-reservation 
trust lands, Puerto Rico, and the Island Areas. In accordance with the 
final criteria, the Census Bureau may modify and, if necessary, reject 
any proposals for block groups that do not meet the established 
criteria. In addition, the Census Bureau reserves the right to modify 
the boundaries and attributes of block groups as needed to meet the 
published criteria and/or maintain geographic relationships before the 
final tabulation geography is set for the 2010 Census.
    The Census Bureau proposes the following criteria for use in 
delineating 2010 Census block groups.
    1. A block group must comprise a reasonable compact, contiguous 
land area.

[[Page 17339]]

    Noncontiguous boundaries are permitted only where a contiguous area 
or inaccessible area would not meet population or housing unit count 
requirements for a separate block group, in which case the 
noncontiguous or inaccessible area must be combined within an adjacent 
or proximate block group. For example, an island that does not meet the 
minimum population threshold for recognition as a separate block group 
should be combined with other proximate land to form a single block 
group. Each case will be reviewed and accepted at the Census Bureau's 
discretion.
    2. Block groups must not cross census tract boundaries.
    This criterion supersedes all population and housing unit 
requirements or guidelines. By extension, because census tracts cannot 
cross county and state boundaries, neither can block groups. It is only 
permissible to define a standard block group with less than 1,200 
people in a county that has a population less than 1,200.
    3. Block groups must cover the entire land and water area of each 
census tract.
    Because census tracts must cover the entire area of a county, by 
definition block groups also must cover the entire area of each county. 
In counties containing coastal waters, territorial sea, and portions of 
the Great Lakes, and very large, contiguous, inland water bodies, a 
single water body tract and a coextensive block group should be created 
for each discrete water body to provide for complete census block group 
coverage.
    4. Block group boundaries should follow visible and identifiable 
features.
    To make the location of block group boundaries less ambiguous, 
wherever possible, block group boundaries should follow visible and 
identifiable features. The Census Bureau also permits the use of state 
and county boundaries in all states and incorporated place and minor 
civil division boundaries in states where those boundaries tend to 
remain unchanged over time (see Table 1). The use of visible features 
also makes it easier to locate and identify block group boundaries over 
time as the locations of many visible features in the landscape tend to 
change infrequently.
    The following features are preferred as block group boundaries for 
the 2010 Census:
    a. State, county, and census tract boundaries must always be block 
group boundaries. This criterion takes precedence over all other 
criteria or requirements.
    b. American Indian reservation and off-reservation trust land 
boundaries.
    c. Visible, perennial natural and cultural features, such as roads, 
shorelines, rivers, perennial streams and canals, railroad tracks, or 
above-ground high-tension power lines.
    d. Boundaries of legal and administrative entities in selected 
states. Table 1 identifies by state which minor civil division (MCD) 
and incorporated place boundaries may be used as block group 
boundaries.

                           Table 1.--Acceptable MCD and Incorporated Place Boundaries
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                                                                         Boundaries
                                                                         of MCDs not
                                                                         coincident
                                                                          with the         All          Only
                                                             All MCD     boundaries   incorporated    conjoint
                       Boundaries                          boundaries        of           place     incorporated
                                                                        incorporated   boundaries       place
                                                                         places that                 boundaries
                                                                         themselves
                                                                          are MCDs
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Alabama.................................................  ............  ............  ............            X
Alaska..................................................  ............  ............  ............            X
Arizona.................................................  ............  ............  ............            X
Arkansas................................................  ............  ............  ............            X
California..............................................  ............  ............  ............            X
Colorado................................................  ............  ............  ............            X
Connecticut.............................................            X   ............            X   ............
Delaware................................................  ............  ............  ............            X
Florida.................................................  ............  ............  ............            X
Georgia.................................................  ............  ............  ............            X
Hawaii..................................................  ............  ............  ............            X
Idaho...................................................  ............  ............  ............            X
Illinois................................................  ............        X \a\   ............            X
Indiana.................................................            X   ............  ............            X
Iowa....................................................  ............            X   ............            X
Kansas..................................................  ............            X   ............            X
Kentucky................................................  ............  ............  ............            X
Louisiana...............................................  ............  ............  ............            X
Maine...................................................            X   ............            X   ............
Maryland................................................  ............  ............  ............            X
Massachusetts...........................................            X   ............            X   ............
Michigan................................................  ............            X   ............            X
Minnesota...............................................  ............            X   ............            X
Mississippi.............................................  ............  ............  ............            X
Missouri................................................  ............        X \b\   ............            X
Montana.................................................  ............  ............  ............            X
Nebraska................................................  ............        X \a\   ............            X
Nevada..................................................  ............  ............  ............            X
New Hampshire...........................................            X   ............            X   ............
New Jersey..............................................            X   ............            X   ............
New Mexico..............................................  ............  ............  ............            X
New York................................................            X   ............            X   ............
North Carolina..........................................  ............  ............  ............            X

[[Page 17340]]

 
North Dakota............................................  ............            X   ............            X
Ohio....................................................  ............            X   ............            X
Oklahoma................................................  ............  ............  ............            X
Oregon..................................................  ............  ............  ............            X
Pennsylvania............................................            X   ............            X   ............
Rhode Island............................................            X   ............            X   ............
South Carolina..........................................  ............  ............  ............            X
South Dakota............................................  ............            X   ............            X
Tennessee...............................................  ............  ............  ............            X
Texas...................................................  ............  ............  ............            X
Utah....................................................  ............  ............  ............            X
Vermont.................................................            X   ............            X   ............
Virginia................................................  ............  ............  ............            X
Washington..............................................  ............  ............  ............            X
West Virginia...........................................  ............  ............  ............            X
Wisconsin...............................................  ............            X   ............            X
Wyoming.................................................  ............  ............  ............           X
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\a\ Townships only.
\b\ Governmental townships only.

    e. Additionally, the following legally defined, administrative 
boundaries would be permitted as block group boundaries:
    i. Barrio, barrio-pueblo, and subbarrio boundaries in Puerto Rico;
    ii. Census subdistrict boundaries in the U.S. Virgin Islands;
    iii. County and island boundaries (both MCD equivalents) in 
American Samoa;
    iv. Election district boundaries in Guam;
    v. Municipal district boundaries in the Commonwealth of the 
Northern Mariana Islands; and
    vi. Alaska Native regional corporation boundaries in Alaska, at the 
discretion of the Census Bureau, insofar as such boundaries are 
unambiguous for allocating living quarters as part of 2010 Census 
activities.
    f. When acceptable visible and governmental boundary features are 
not available for use as block group boundaries, the Census Bureau may, 
at its discretion, approve other nonstandard visible features, such as 
ridge lines, above-ground pipelines, intermittent streams, or fence 
lines. The Census Bureau may also accept, on a case-by-case basis, the 
boundaries of selected nonstandard and potentially nonvisible features, 
such as the boundaries of military installations, National Parks, 
National Monuments, National Forests, other types of parks or forests, 
airports, marine ports, cemeteries, golf courses, penitentiaries/
prisons, glaciers, or the straight-line extensions of visible features 
and other lines-of-sight.
    g. The boundaries of large water bodies and special land use 
tracts, including parks, forests, and military installations, provided 
the boundaries are clearly marked or easily recognized.
5. Population, Housing Unit, and Area Thresholds
    The Census Bureau proposes the following population, housing unit, 
and area threshold criteria for census block group (as suggested in 
Table 2). Any block group that does not meet the minimum population or 
housing unit threshold must be revised.

                                        Table 2.--Block Group Thresholds
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               Block group type                          Threshold type               Minimum         Maximum
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Standard & tribal block groups................  Population threshold............           1,200           3,000
                                                Housing Unit threshold..........             480          1,200.
Water body block groups.......................  Area threshold (square miles)...             100            none
Special land use block groups.................  Area threshold for an urban area               1            none
                                                 (square miles).
                                                Area threshold outside an urban               10            none
                                                 area (square miles).
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    a. Census 2000 population counts should be used in census block 
group review in most cases. Housing unit counts should be used for 
block groups in seasonal communities that have no or low population on 
census day (April 1). Locally produced population and housing unit 
estimates can be used when reviewing and updating block groups, 
especially in areas that have experienced considerable growth since 
Census 2000.
    b. The housing unit thresholds are based on a national average of 
2.5 persons per household. The Census Bureau recognizes that there are 
regional variations to this average, and will take this into 
consideration when reviewing all census block group proposals.

[[Page 17341]]

    c. For the 2010 Census, the Census Bureau encourages the 
delineation of special use census tracts, hence special use block 
groups, in specific types of areas:
    i. A special land use block group must be designated as a specific 
land use type (e.g. state park), must have an official name (e.g., Jay 
Cooke State Park), have little or no residential population, and must 
not create a noncontiguous block group. In some instances, multiple 
areas can be combined to form a single special land use block group if 
the land management characteristics are similar, such as a special land 
use block group comprising adjacent federal and state parks. If the 
special land use block group is delineated in a densely populated, 
urban area, the block group must have an area of approximately one 
square mile or more. If the special land use block group is delineated 
completely outside an urban area, the block group must have an area of 
approximately 10 square miles or more.
    ii. A water body block group must encompass all or part of a 
territorial sea, coastal water, a Great Lake, or an inland water body 
at least 100 square miles in area. If an inland water body meets this 
criterion and is in more than one county, each county can delineate a 
block group for its portion of the water body. Any islands within a 
qualifying water body should be included within a separate block group.
6. Identification of Block Groups
    a. A block group encompasses a cluster of census blocks. Each block 
group is identified using a single-digit number that will correspond to 
the first digit in the number of each block that comprises it. For 
example, census block group 3 includes all census blocks numbered in 
the 3000 range within a single census tract.
    b. The range of acceptable block group numbers is 1 through 9. 
Block group numbers must always be unique within a census tract.
7. Block Group Types

   Table 3.--Table 3 Below Contains a Summary of the Types of Block Groups (With Their Respective Population,
  Housing Unit and Area Characteristics) That the Census Bureau Proposes To Use for the 2010 Census. Summary of
                                                Block Group Types
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                                   How distinct from
                                    standard block        Population         Housing unit       Area thresholds
                                        groups            thresholds          thresholds
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Standard & tribal block groups..  Tribal block        Minimum: 1,200;     Minimum: 480;       none.
                                   groups are          Maximum: 3,000.     Maximum: 1,200.
                                   conceptually
                                   similar and
                                   equivalent to
                                   census block
                                   groups defined
                                   within the
                                   standard state-
                                   county-tract-
                                   block group
                                   geographic
                                   hierarchy used
                                   for tabulating
                                   and publishing
                                   statistical data.
Water body block groups.........  A block group       Zero..............  Zero..............  100 square miles
                                   coextensive with                                            if an inland
                                   a water body                                                water body.
                                   tract,
                                   encompassing all
                                   or part of a
                                   territorial sea,
                                   coastal water, a
                                   Great Lake, or an
                                   inland water body
                                   at least 100
                                   square miles area.
Special land use block groups...  A block group       Little or none....  Little or none....  one square mile
                                   coextensive with                                            within an urban
                                   a special land                                              area/ten square
                                   use tract,                                                  miles outside an
                                   encompassing a                                              urban area.
                                   large airport,
                                   public park, or
                                   public forest
                                   with little or no
                                   population or
                                   housing units. In
                                   a densely
                                   populated, urban
                                   area, a special
                                   land use block
                                   group must be
                                   approximately one
                                   square mile in
                                   area or greater.
                                   If delineated
                                   completely
                                   outside an urban
                                   area, a special
                                   land use block
                                   group must have
                                   an area of ten
                                   square miles or
                                   greater.
----------------------------------------------------------------------------------------------------------------

D. Tribal Block Groups

    Tribal block groups are statistical geographic entities defined by 
the Census Bureau in cooperation with tribal officials to provide 
meaningful, relevant, and reliable data for small geographic areas 
within the boundaries of federally recognized American Indian 
reservations and/or off-reservation trust lands. As such, they 
recognize the unique statistical data needs of federally recognized 
American Indian tribes. The delineation of tribal block groups allows 
for an unambiguous presentation of statistical data specific to a 
federally recognized reservation and/or off-reservation trust lands 
without the imposition of state or county boundaries, which might 
artificially separate American Indian populations located within a 
single reservation and/or off-reservation trust land. To this end, the 
American Indian tribal participant \5\ may define tribal block groups 
that cross county or state boundaries, or both. Tribal block groups 
must be delineated to meet all other census block group criteria, and 
must be numbered uniquely so as to clearly distinguish them from 
county-based block groups. Tribal block group boundaries will be held 
as census block boundaries. Census blocks, however, will be numbered 
uniquely within county-based block groups. Tribal block groups are 
conceptually similar and equivalent to census block groups defined 
within the standard state-county-tract-block group geographic hierarchy 
used for tabulating and publishing statistical data.
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    \5\ For federally recognized American Indian tribes with 
reservations and/or off-reservation trust lands that have more than 
2,400 residents, the Census Bureau will offer the tribal government 
the opportunity to delineate tribal block groups and other tribal 
statistical geography on their reservation and/or off-reservation 
trust land. For federally recognized tribes with an American Indian 
reservation and/or off-reservation trust land that have fewer than 
2,400 residents, the Census Bureau will define one tribal tract and 
one tribal block group coextensive with the American Indian 
reservation and/or off-reservation trust land.
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    In order to provide meaningful statistical geographic areas within 
the reservation and/or off-reservation trust land, as well as make 
meaningful and reliable data available for these areas and their 
populations, the Census Bureau proposes that for the 2010 Census, 
standard block groups be delineated nationwide, and the tribal

[[Page 17342]]

block group geography be maintained separately, and defined through a 
separate program designed specifically for tribal statistical 
geography. This differs from the procedure for Census 2000 in which 
tribal block groups were defined for federally recognized American 
Indian reservations and/or off-reservation trust lands, and standard 
block groups were identified by superimposing county and state 
boundaries onto the tribal block groups.
    For Census 2000 products in which data were presented by state and 
county, the standard state-county-census tract-block group hierarchy 
was maintained, even for territory contained within an American Indian 
reservation and/or off-reservation trust land. In such instances, the 
state/county portions of tribal block groups were identified as 
individual block groups, and these standard block groups may not have 
met the minimum population or housing unit thresholds, potentially 
limiting sample data reliability or availability for both the tribal 
block group and the derived standard block groups. The proposed change 
in the tribal block group program for the 2010 Census, creating 
standard block groups nationwide and maintaining tribal block groups as 
a completely separate set of geography from standard block groups in 
both geographic and data presentation purposes, seeks to eliminate, in 
part, these data issues from Census 2000.
    As with standard block groups submitted through the program, the 
tribal block groups would be submitted to the Census Bureau, and would 
be subject to review to ensure compliance with the final published 
criteria. Tribal block groups will be defined as part of a separate 
Tribal Statistical Areas Program (TSAP) for the 2010 Census. Detailed 
criteria pertaining to tribal block groups will be published in a 
separate Federal Register notice pertaining to all American Indian 
statistical areas defined through the TSAP.

III. Definitions of Key Terms

    Alaska Native regional corporation (ANRC)--A corporate geographic 
area established under the Alaska Native Claims Settlement Act (Pub. L. 
92-203), to conduct both, the business and nonprofit affairs of Alaska 
Natives. Twelve ANRCs cover the entire State of Alaska except for the 
Annette Island Reserve.
    American Indian off-reservation trust land (ORTL)--A federally 
recognized American Indian land area located outside the boundaries of 
an American Indian reservation whose boundaries are established by deed 
and over which a federally recognized American Indian tribal government 
has governmental authority.
    American Indian reservation (AIR)--A federally recognized American 
Indian land area with boundaries established by final treaty, statute, 
executive order, and/or court order and over which a federally 
recognized American Indian tribal government has governmental 
authority. Along with reservation, designations such as colonies, 
communities, pueblos, rancherias, and reserves apply to AIRs.
    Coastal water--Water bodies between territorial seas and inland 
water, the encompassing headlands being more than one mile apart and 
less than 24 miles apart.
    Conjoint--A description of a boundary shared by two adjacent 
geographic entities.
    Contiguous--A description of areas sharing common boundaries, such 
that the areas, when combined, form a single piece of territory. 
Noncontinuous areas form disjoint pieces.
    Great Lakes' waters--Water area beyond one mile wide headland 
embayments located in any of the five Great Lakes: Erie, Huron, 
Michigan, Ontario, or Superior.
    Group quarters (GQ)--A place where people live or stay, in a group 
living arrangement, that is owned or managed by an entity or 
organization providing housing and/or services for the residents. This 
is not a typical household-type living arrangement. These services may 
include custodial or medical care, as well as other types of 
assistance, and residency is commonly restricted to those receiving 
these services. People living in group quarters are usually not related 
to each other. Group quarters include such places as college residence 
halls, residential treatment centers, skilled nursing facilities, group 
homes, military barracks, correctional facilities, and workers' 
dormitories.
    Incorporated place--A type of governmental unit, incorporated under 
state law as a city, town (except in New England, New York, and 
Wisconsin), borough (except in Alaska and New York), or village, 
generally to provide governmental services for a concentration of 
people within legally prescribed boundaries.
    Inland water--Water bodies entirely surrounded by land or at the 
point where their opening to coastal waters, territorial seas, or the 
Great Lakes is less than one mile across.
    Minor civil division (MCD)--The primary governmental or 
administrative division of a county in 28 states and the Island Areas 
having legal boundaries, names, and descriptions. MCDs represent many 
different types of legal entities with a wide variety of 
characteristics, powers, and functions depending on the state and type 
of MCD. In some states, some or all of the incorporated places also 
constitute MCDs.
    Nonvisible feature--A map feature that is not visible on the 
ground, such as a city or county boundary through space, a property 
line, line-of-sight extension of a road.
    Special land use block group--Block group delineated coextensive 
with, or covering the same area as, the special land use tract.
    Special land use tract--Type of census tract that must be 
designated as a specific land use type (e.g. state park) and have an 
official name (e.g., Jay Cooke State Park), must have little or no 
residential population or housing units, and must not create a 
noncontiguous census tract. If delineated in a densely populated, urban 
area, a special land use tract must have an area of approximately one 
square mile or more. If delineated completely outside an urban area, a 
special land use tract must have an area of approximately 10 square 
miles or more.
    Territorial seas--Water bodies not included under the definition 
for inland water, coastal water, or Great Lakes' waters, see above.
    TIGER--Topologically Integrated Geographic Encoding and Referencing 
database developed by the Census Bureau to support its mapping needs 
for the Decennial Census and other Census Bureau programs. The 
topological structure of the TIGER database defines the location and 
relationship of boundaries, streets, rivers, railroads, and other 
features to each other and to the numerous geographic areas for which 
the Census Bureau tabulates data from its censuses and surveys.
    Visible feature--A map feature that can be seen on the ground, such 
as a road, railroad track, major above-ground transmission line or 
pipeline, river or stream, shoreline, fence, sharply defined mountain 
ridge, or cliff. A nonstandard visible feature is a feature that may 
not be clearly defined on the ground (such as a ridge), may be seasonal 
(such as an intermittent stream), or may be relatively impermanent 
(such as a fence). The Census Bureau generally requests verification 
that nonstandard features used as boundaries for the PSAP geographic 
areas pose no problem in their location during field work.
    Water body block group--Block group delineated coextensive with, or 
covering the same area as, the water body tract.

[[Page 17343]]

    Water body tract--Type of census tract encompassing territorial 
seas, coastal water, the Great Lakes, or inland water at least 100 
square miles in area. If an inland water body meets this criteria, each 
county can delineate a census tract for its portion of the water body.

Executive Order 12866

    This notice has been determined to be not significant under 
Executive Order 12866.

Paperwork Reduction Act

    This program notice does not represent a collection of information 
subject to the requirements of the Paperwork Reduction Act, 44 U.S.C. 
Chapter 35.

    Dated: April 3, 2007.
Charles Louis Kincannon,
Director, Bureau of the Census.
 [FR Doc. E7-6467 Filed 4-5-07; 8:45 am]
BILLING CODE 3510-07-P