[Federal Register Volume 86, Number 32 (Friday, February 19, 2021)]
[Notices]
[Pages 10237-10243]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03412]


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DEPARTMENT OF COMMERCE

Bureau of the Census

[Docket Number 210212-0021]


Urban Areas for the 2020 Census--Proposed Criteria

AGENCY: Bureau of the Census, Department of Commerce.

ACTION: Notice of proposed program and request for comments.

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SUMMARY: This notice provides the Bureau of the Census' (hereafter, 
Census Bureau's) proposed criteria for defining urban areas based on 
the results of the 2020 Decennial Census. It also provides a 
description of the changes from the final criteria used for the 2010 
Census. The Census Bureau is requesting public comment on these 
proposed criteria. The Census Bureau delineates urban areas after each 
decennial census by applying specified criteria to decennial census and 
other data. Since the 1950 Census, the Census Bureau has reviewed and 
revised these criteria, as necessary, for each decennial census in 
order to improve the classification of urban areas by taking advantage 
of newly available data and advancements in geographic information 
processing technology.

DATES: Written comments must be submitted on or before May 20, 2021.

ADDRESSES: Please direct all written comments on this proposed program 
via email at [email protected] to Vincent Osier, Geographic 
Standards, Criteria, and Quality Branch, Geography Division, U.S. 
Census Bureau. Please note that paper comments cannot be reviewed due 
to limited building access caused by the COVID-19 pandemic. Phone: 301-
763-1128.

FOR FURTHER INFORMATION CONTACT: Requests for additional information on 
this proposed program should be directed to Vincent Osier, Geographic 
Standards, Criteria, and Quality Branch, Geography Division, U.S. 
Census Bureau, via email at [email protected]. Phone: 301-763-1128.

SUPPLEMENTARY INFORMATION: The Census Bureau's urban area 
classification is fundamentally a delineation of geographical areas, 
identifying individual urban areas as well as the rural portion of the 
nation. The Census Bureau's urban areas represent densely developed 
territory, and encompass residential, commercial, and other non-
residential urban land uses. The boundaries of the urban areas have 
been defined primarily by using measures based on population counts and 
residential population density, and also by using measures based on 
criteria that account for non-residential urban land uses, such as 
commercial, industrial, transportation, and open space that are part of 
the urban landscape. Since the 1950 Census, when the Census Bureau 
first defined densely settled urbanized areas of 50,000 or more people, 
the urban area delineation process has addressed non-residential urban 
land uses through criteria designed to account for commercial enclaves, 
special land uses such as airports, and densely developed noncontiguous 
territory.
    In delineating urban areas, the Census Bureau does not take into 
account or attempt to meet the requirements of any nonstatistical uses 
of these areas or their associated data. Nonetheless, the Census Bureau 
recognizes that some federal and state agencies use the Census Bureau's 
urban area classification for nonstatistical uses such as allocating 
program funds, setting program standards, and implementing aspects of 
their programs. The agencies that use the classification and data for 
such nonstatistical uses should be aware that the changes to the urban 
area criteria also might affect the implementation of their programs. 
In addition, the Census Bureau is not responsible for the use of its 
urban area classification in nonstatistical programs. If a federal, 
tribal, state, or local agency uses the urban area classification for 
nonstatistical purposes, it is that agency's responsibility to ensure 
that the classification is appropriate for such use.

(1) History

    Over the course of a century defining urban areas, the Census 
Bureau has introduced conceptual and methodological changes to ensure 
that the urban area classification keeps pace with changes in 
settlement patterns and with changes in theoretical and practical 
approaches to interpreting and understanding the definition of urban 
areas. Prior to the 1950 Census, the Census Bureau primarily defined 
``urban'' as any population, housing,

[[Page 10238]]

and territory located within incorporated places with a population of 
2,500 or more. That definition was easy and straightforward to 
implement, requiring no need to calculate population density; to 
understand and account for actual settlement patterns on the ground in 
relation to boundaries of administrative units; or to consider densely 
settled populations existing outside incorporated municipalities. For 
much of the first half of the twentieth century, that definition was 
adequate for defining ``urban'' and ``rural'' in the United States, but 
by 1950 it became clear that it was incomplete.
    Increasing suburbanization, particularly outside the boundaries of 
large incorporated places led the Census Bureau to adopt the urbanized 
area concept for the 1950 Census. At that time, the Census Bureau 
formally recognized that densely settled communities outside the 
boundaries of large incorporated municipalities were just as ``urban'' 
as the densely settled population inside those boundaries. Outside of 
urbanized areas of 50,000 or more people, the Census Bureau continued 
to recognize urban places with at least 2,500 and less than 50,000 
persons. This basic conceptual approach to identifying urban areas 
remained in effect through the 1990 Census, albeit with some changes to 
criteria and delineation methods.
    The Census Bureau adopted six substantial changes to its urban area 
criteria for the 2000 Census:
     Defining urban clusters using the same criteria as 
urbanized areas.
     Disregarding incorporated place and census designated 
place (CDP) boundaries when defining urbanized areas and urban 
clusters.
     Adoption of 500 persons per square mile (ppsm) as the 
minimum density criterion for recognizing some types of urban 
territory.
     An increase in the maximum jump distance for linking 
densely developed territory separated from the main body of the urban 
area by intervening low density territory from 1.5 to 2.5 miles. This 
recognized the prospect that larger clusters of non-residential urban 
uses might offset contiguity of densely settled territory.
     Introduction of the hop concept to provide an objective 
basis for recognizing that nonresidential urban uses, such as small 
commercial areas or parks, create small gaps between densely settled 
residential territories, but are part of the pattern of urbanization.
     Adoption of a zero-based approach to defining urban areas.
    For the 2010 Census, the Census Bureau adopted moderate changes and 
enhancements to the criteria to improve upon the classification of 
urban and rural areas while continuing to meet the objective of a 
uniform application of criteria nationwide. These changes were:
     Use of census tracts as analysis units in the initial 
phase of delineation.
     Use of land use/land cover data from the National Land 
Cover Database (NLCD) to identify qualifying areas of non-residential 
urban land uses.
     Qualification of airports for inclusion in urban areas.
     Elimination of the designation of central places within 
urban areas.\1\
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    \1\ The central place concept was not necessary for urban area 
delineation and the resulting list of qualified central places 
largely duplicated the list of principal cities identified by the 
Metropolitan and Micropolitan Statistical Area standards. There was 
no conceptual reason to continue identifying two slightly different 
lists of cities and other places that were central to their 
respective regions.
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     Requirement for minimum population residing outside 
institutional group quarters.
     Splitting large urban agglomerations.
    The conceptual and criteria changes adopted for both the 2000 and 
2010 Censuses, as well as the history of the Census Bureau's urban area 
classification, are discussed in more detail in the document ``A 
Century of Delineating a Changing Landscape: The Census Bureau's Urban 
and Rural Classification, 1910 to 2010,'' available at https://www2.census.gov/geo/pdfs/reference/ua/Century_of_Defining_Urban.pdf.

(2) Proposed Changes for the 2020 Urban Areas

Adoption of a Housing Unit Density Threshold for Qualification of 
Census Blocks

    The Census Bureau proposes adopting a housing unit density 
threshold of 385 housing units per square mile as the primary criterion 
for determining whether a census block qualifies for inclusion in an 
urban area, replacing the use of population density. The 385 housing 
units (occupied or vacant) per square mile density threshold utilized 
in the delineation of urban areas is consistent with the 1,000 persons 
per square mile density used in the past, based on the 2019 American 
Community Survey (ACS) 1-year data average of an estimated 2.6 persons 
per household for the United States. Housing unit density provides a 
more direct measure of the densely developed landscape than population 
density. The use of housing unit density will allow the Census Bureau 
to more accurately account for areas with substantial concentrations of 
housing that are considered part of the urban landscape, but have 
smaller than average persons per housing unit or seasonal populations 
or both. This change also will provide the ability to update the extent 
of urban areas between censuses, based on housing unit information in 
the Census Bureau's Master Address File. Intercensal updates of urban 
areas have not been possible to date, due to the lack of population 
counts at the census block-level between decennial censuses. As a 
result, although the Census Bureau presented estimated populations for 
urban areas based on the ACS, these data were produced using boundaries 
defined based on data from the previous decennial census and did not 
keep pace with changes to the extent of urbanization. In addition, the 
Census Bureau's decision to adopt differential privacy methodology as a 
means for protecting the privacy of individual responses to the 
decennial census has been accompanied by the decision that published 
census block-level populations should be variant--that is, the 
published population count for any given census block will vary from 
the enumerated population count in order to protect individuals from 
reidentification. This will affect the calculation of population 
density at the census block-level. Housing unit counts, however, are 
invariant and will reflect the number of housing units enumerated in 
each block, and thus are a more consistent measure.

Qualify Urban Areas Based on a Minimum Threshold of 4,000 Housing Units 
or 10,000 Persons Instead of a Minimum Threshold of 2,500 Persons

    The Census Bureau proposes that an area will qualify as urban if it 
contains at least 4,000 housing units or has a population of at least 
10,000. The proposed increase in the minimum population responds to 
calls for the Census Bureau to increase its minimum threshold for 
defining urban areas from the 2,500-person minimum established in 1910. 
The proposed 10,000-person minimum threshold aligns with thresholds 
used by other federal agencies to distinguish between urban and rural 
areas as well as with the Office of Management and Budget's minimum 
threshold for urban areas that form the cores of micropolitan 
statistical areas. The proposal to adopt a housing unit threshold is 
consistent with our proposed shift to housing unit density and is 
proposed for the same reasons: It provides a more direct measure of 
settlement and the built environment

[[Page 10239]]

and bases qualification on a measure that is not subject to variance 
resulting from the Census Bureau's disclosure avoidance methodology. 
The proposed 4,000-housing unit threshold approximates the 10,000-
person threshold based on the national average of 2.6 persons per 
household. We are proposing use of either threshold for qualification 
of an area as urban, based on the recognition that some areas have 
average persons per household sizes larger than the national average of 
2.6, or may contain a substantial number of persons living in group 
quarters (or both), and, as a result, may have populations of 10,000 or 
more, but less than 4,000 housing units.

Cease Distinguishing Different Types of Urban Areas

    The Census Bureau proposes to cease distinguishing different types 
of urban areas. In adopting this proposal, the Census Bureau would 
identify urban areas of 4,000 or more housing units or 10,000 or more 
persons without distinguishing types of urban areas. The 50,000-person 
threshold that has been used to distinguish between urbanized areas and 
smaller urban areas (whether urban places outside urbanized areas or 
urban clusters) no longer has the same meaning as when it was adopted 
in 1950 and, therefore, should no longer be used to distinguish types 
of urban areas. Further, the threshold is, to some extent, arbitrary; 
that is, as far as the Census Bureau has been able to determine from 
scholarship, there is no reason to assume that an urban area of just 
over 50,000 persons is fundamentally different in terms of economic and 
social functions and services than an area with just under 50,000 
persons. Lastly, federal agencies apply a range of thresholds to 
various urban-rural classifications. These thresholds can be applied to 
the published data by the individual agencies to meet their own 
objectives.

Maximum Distances of Jumps

    Jumps (and the shorter distance hops) recognize that urban 
development is not always a continuous and contiguous process across 
the landscape, and facilitate inclusion of noncontiguous densely 
developed territory that is considered part of the nearby urban area. 
(For more information about the history and evolution of the jump and 
hop concepts, see ``A Century of Delineating a Changing Landscape: The 
Census Bureau's Urban and Rural Classification, 1910 to 2010,'' 
available at https://www2.census.gov/geo/pdfs/reference/ua/Century_of_Defining_Urban.pdf.) The Census Bureau proposes reducing the 
maximum jump distance to 1.5 miles, returning to the maximum distance 
employed in urban area delineation from the 1950 Census through the 
1990 Census. Data users, analysts, and some urban geographers expressed 
concern that the 2.5 mile maximum jump distance adopted for the 2000 
Census was too generous in some situations and resulted in 
overextension of urban area territory. The Census Bureau proposed 
reverting to 1.5 miles in the proposed criteria for the 2010 Census, 
but responses from commenters were inconclusive and, as a result, no 
change was made. We continue to be concerned about the possible 
overextension of urban area territory in some situations as a result of 
the 2.5 mile maximum jump distance. The impervious surface criteria 
adopted in 2010 accounted for non-residential urban land uses, many of 
which also were in mind when we extended the jump distance for the 2000 
Census. Thus, the two criteria serve largely the same purpose, but are 
applied separately, and when taken together, they can result in 
overextension of urban territory.

No Longer Include the Low Density Hop or Jump ``Corridor'' in the Urban 
Area

    The Census Bureau proposes to no longer include within an urban 
area the low density territory intervening between the main body of the 
urban area and the outlying qualifying territory that is the 
destination of a hop or a jump or exempted territory that has been 
separated from the urban area core by water or wetlands. This will 
result in noncontiguous urban areas. Review of 2010 Census urban areas 
indicates that, due to their often irregular and relatively large 
geographic extent, including the corridor blocks sometimes resulted in 
the inclusion of population, housing, and territory that is otherwise 
of a rural nature and contains land uses that are not consistent with 
those found in the densely developed blocks on either end of the hop or 
jump corridor. We note that the 1950 Census criteria for defining 
urbanized areas, while permitting jumps of up to 1.5 miles across low 
density intervening territory, did not call for inclusion of the low 
density jump corridor in the urban area. This change in criteria will 
result in a more accurate depiction of the patterns of urban 
development.

No Longer Include Low-Density Territory Located Within Indentations 
Formed During the Urban Area Delineation Process

    Consistent with concerns about overbounding of urban areas and with 
the decision to no longer include the low-density hop and jump 
corridors within urban areas, we propose to cease including low-density 
territory within indentations that are formed during the delineation 
process when densely developed, qualifying territory surrounds low-
density territory on three sides. Previous urban area criteria provided 
for the inclusion of indentations, when specified conditions were met, 
to (1) account for potential non-residential urban land uses that may 
be located within the indentation, (2) account for the potential for 
higher density development in the near future, and (3) produce 
smoother, less complicated boundaries for mapping purposes. Review of 
land uses within indentations formed during the 2010 urban area 
delineation has indicated that much of the territory remains less 
developed and less urban in character. Given that the impervious 
surface criteria are sufficient for identifying non-residential urban 
land uses and that modern computerized mapping and visualization 
methods provide the ability for users to view boundaries are various 
scales or ``zoom levels,'' thus reducing the need for smoother 
boundaries, we no longer see a need to close off indentations when 
delineating urban areas.

Splitting of Large Agglomerations of Densely Settled Territory

    The automated process utilized by the Census Bureau results in the 
delineation of large agglomerations of continuously developed 
territory. While there is value in the identification of large 
agglomerations, some are too large and extensive to be of use for most 
analyses involving urban areas. Examples of large agglomerations of 
continuously developed territory exist throughout the United States and 
Puerto Rico, some encompassing only a pair of urban areas; others 
encompassing three or more urban areas extending across multiple 
states.
    The question of when and how to merge adjacent urban areas or split 
large agglomerations has existed since the delineation of urban areas 
for the 1960 Census. Past criteria relied upon metropolitan statistical 
area or primary metropolitan statistical area definitions to determine 
whether to merge adjacent urban areas or, as was the case in the 2010 
Census criteria, split agglomerations based on the previous decade's 
urbanized areas. Neither of these approaches relied upon objective 
measures consistent with the same time frame as the measures used in 
the delineation process. In other words, agglomerations were delineated 
based

[[Page 10240]]

on data either from or contemporary with the decennial census, but were 
split based on the results of the previous decade's data and 
delineation.
    For the 2020 Census, the Census Bureau proposes using worker flow 
data (i.e., commuting flows) from the Longitudinal Employer-Household 
Dynamics (LEHD) Program to identify whether the agglomeration 
represents a single functionally integrated region or whether commuting 
patterns indicate the presence of distinct urban areas within the 
larger agglomeration. The LEHD worker flow data would be used in two 
stages. The first stage is an analysis of adjacent 2010 Census urban 
areas, based on aggregate commuter flows into and out of each urban 
area. Adjacent 2010 Census urban areas will be merged if 50 percent or 
more of the workers in the smaller urban area are working in the larger 
urban area and 50 percent or more of the jobs in the smaller urban area 
are filled by workers residing in the larger urban area. If not merged, 
urban areas are selected for further analysis and split boundary 
adjustment. The second stage is identification of where to split large 
agglomerations, based on patterns observed by performing ``community'' 
detection on the LEHD worker flow data. ``Community'' boundaries 
resulting from application of the Leiden Algorithm \2\ to the worker 
flow data will be used to adjust 2010 Census urban area split 
boundaries for the final 2020 Census urban areas. Application of this 
criterion could shift territory from one 2010 urban area to a different 
2020 urban area. The resulting splits will reflect contemporaneous 
commuting patterns, which in turn, serve as proxy measures for other 
kinds of economic and social interactions within urban areas.
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    \2\ Thomas, I., A. Adam, and A. Verhetsel. Migration and 
commuting interactions fields: A new geography with community 
detection algorithm? 2017. Belgeo. [Online], 4. http://journals.openedition.org/belgeo/20507. Traag V.A, L. Waltman and 
N.J. van Eck. From Louvain to Leiden: Guaranteeing well-connected 
communities. 2019. Scientific Reports. 9:5233.
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(3) Proposed Urban Area Criteria for the 2020 Census

    The proposed criteria outlined herein apply to the United 
States,\3\ Puerto Rico, and the Island Areas of American Samoa, the 
Commonwealth of the Northern Mariana Islands, Guam, and the U.S. Virgin 
Islands. The Census Bureau proposes the following criteria and 
characteristics for use in identifying the areas that will qualify for 
designation as urban areas for use in tabulating data from the 2020 
Census, the American Community Survey (ACS), the Puerto Rico Community 
Survey, and potentially other Census Bureau censuses and surveys.
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    \3\ For Census Bureau purposes, the United States includes the 
50 States and the District of Columbia.
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A. 2020 Census Urban Area Definitions

    For the 2020 Census, an urban area will comprise a densely 
developed core of census blocks \4\ that meet minimum housing unit 
density requirements, along with adjacent territory containing non-
residential urban land uses as well as other lower density territory 
included to link outlying densely settled territory with the densely 
settled core. To qualify as an urban area, the territory identified 
according to the proposed criteria must encompass at least 4,000 
housing units or at least 10,000 persons. The term ``rural'' 
encompasses all population, housing, and territory not included within 
an urban area.
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    \4\ A census block is the smallest geographic area for which the 
Census Bureau tabulates data and is an area normally bounded by 
visible features, such as streets, rivers or streams, shorelines, 
and railroads, and by nonvisible features, such as the boundary of 
an incorporated place, minor civil division, county, or other 2020 
Census tabulation entity.
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    As a result of the urban area delineation process, an incorporated 
place or census designated place (CDP) may be partly inside and partly 
outside an urban area. Any census geographic areas, with the exception 
of census blocks, may be partly within and partly outside an urban 
area.
    All proposed criteria based on land area, housing unit density, and 
population, reflect the information contained in the Census Bureau's 
Master Address File/Topologically Integrated Geographic Encoding and 
Referencing (MAF/TIGER) Database (MTDB) at the time of the initial 
delineation. All calculations of housing unit density include only 
land; the areas of water contained within census blocks are not used in 
density calculations. Housing unit, population, and worker flow data 
used in the urban area delineation process will be those published by 
the Census Bureau for all public and official uses.

B. Proposed Urban Area Delineation Criteria

    The Census Bureau proposes to define urban areas primarily on the 
basis of housing unit density measured at the census block level of 
geography. The 385 housing units per square mile density threshold 
utilized in the delineation of urban areas is consistent with the 1,000 
persons per square mile density used in the past, based on the 2019 ACS 
1-year data average of an estimated 2.6 persons per household for the 
United States.
1. Identification of Initial Urban Area Cores
    The Census Bureau proposes to begin the delineation process by 
identifying and aggregating contiguous census blocks each having a 
housing unit density of at least 385 housing units per square mile. 
This aggregation of continuous census blocks would be known as the 
``initial urban area core.'' The initial urban area core must encompass 
at least 385 housing units (consistent with the requirement for at 
least 1,000 people in the 2010 criteria).
    After the initial urban area core is identified, additional census 
blocks would be included if it is adjacent to other qualifying 
territory and if it meets any of the following criteria:
    a. It has a housing unit density of at least 385 housing units per 
square mile.
    b. At least one-third of the census block consists of territory 
with a level of imperviousness of at least twenty percent,\5\ and is 
compact in nature as defined by a shape index. A census block is 
considered compact when the shape index is at least 0.185 using the 
following formula: I = 4[pi]A/P\2\ where I is the shape index, A is the 
area of the entity, and P is the perimeter of the entity.
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    \5\ The Census Bureau has found in testing the NLCD that 
territory with an impervious percent less than twenty percent 
results in the inclusion of road and structure edges, and not the 
actual roads or buildings themselves.
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    c. At least one-third of the census block consists of territory 
with a level of imperviousness of at least twenty percent, and at least 
forty percent of its boundary is contiguous with qualifying territory.
    The Census Bureau would apply proposed criteria 1.a, 1.b, and 1.c 
above until there are no blocks to add to the urban area. Any ``holes'' 
or remaining nonqualifying territory completely contained within an 
initial urban area core that is less than five square miles in area 
will qualify as urban via the criteria for inclusion of enclaves, as 
set forth below in the III. B. 5., subheading entitled, ``5. Inclusion 
of Enclaves.''
2. Inclusion of Group Quarters
    Census blocks containing institutional and non-institutional group 
quarters that are adjacent to census blocks qualifying based on the 
criteria outlined in step 1 above (``1. Identification of Initial Urban 
Area Cores'') will be included in the urban area. This criterion 
accounts for the fact that group quarters, such as college dormitories, 
are not considered housing units by the

[[Page 10241]]

Census Bureau, but generally are part of the urban landscape.
3. Inclusion of Noncontiguous Territory via Hops and Jumps
    Noncontiguous territory that meets the proposed housing density 
criteria specified in section B.1.a and b above, but is separated from 
an initial urban area core of 385 housing units or more, may be added 
via a hop along a road connection of no more than 0.5 miles. Multiple 
hops may be made along a single road connection, thus accounting for 
the nature of contemporary urban development, which often encompasses 
alternating patterns of residential and non-residential uses.
    After adding territory to an initial urban area core via hop 
connections, the Census Bureau will identify all urban area cores that 
have a housing unit count of 577 or more (consistent with the 
requirement for at least 1,500 people in the 2010 criteria) and add 
other qualifying territory via a jump connection.\6\ Jumps are used to 
connect densely settled noncontiguous territory separated from the 
urban area core by territory with low housing unit density measuring 
greater than 0.5 and no more than 1.5 road miles across. This process 
recognizes the existence of larger areas of non-residential uses or 
other territory with low housing unit density that do not provide a 
substantial barrier to interaction between outlying territory with high 
housing unit density and the urban area core. Because it is possible 
that any given densely developed area could qualify for inclusion in 
multiple cores via a jump connection, the identification of jumps in an 
automated process starts with the initial urban area core that has the 
largest total population and continues in descending order based on the 
total population of each initial urban area core. Only one jump is 
permitted along any given road connection. This limitation, which has 
been in place since the inception of the urban area delineation process 
for the 1950 Census, prevents the artificial extension of urban areas 
over large distances that result in the inclusion of communities that 
are not commonly perceived as connected to the particular initial urban 
area core. Exempted territory is not taken into account when measuring 
road distances across hop and jump corridors. In the case of both hops 
and jumps, the intervening, low density block or blocks are not 
included in the urban area.
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    \6\ All initial urban area cores with less than 4,000 housing 
units or 10,000 persons are not selected to continue the delineation 
as separate urban areas; however, these cores still are eligible for 
inclusion in an urban area using subsequent proposed criteria and 
procedures.
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4. Inclusion of Noncontiguous Territory Separated by Exempted Territory
    The Census Bureau proposes to identify and exempt territory in 
which residential development is substantially constrained or not 
possible due to either topographical or land use conditions.\7\ Such 
exempted territory offsets urban development due to particular land 
use, land cover, or topographic conditions. For the 2020 Census, the 
Census Bureau proposes the following to be exempted territory:
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    \7\ The land cover and land use types used to define exempted 
territory are limited to only those that are included in or can be 
derived from the Census Bureau's MTDB or the MRLC's most recent 
version of the NLCD nationally, consistently, and with some 
reasonable level of accuracy.
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     Bodies of water; and
     Wetlands (belonging to one of eight wetlands class 
definitions \8\)
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    \8\ For the MRLC's 2016 NLCD, wetlands are identified as 
belonging to one of eight wetlands class definitions including 
woody, palustrine forested, palustrine scrub/shrub, estuarine 
forested, estuarine scrub/shrub, emergent herbaceous, palustrine 
emergent (persistent), or estuarine emergent.
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    Noncontiguous qualifying territory would be added to a core via a 
hop or jump when separated by exempted territory, provided that it 
meets the following criteria:
    a. The road connection across the exempted territory (located on 
both sides of the road) is no greater than five miles, and
    b. The total length of the road connection between the initial 
urban area core and the noncontiguous territory, including the exempt 
distance and non-exempt hop or jump distances, is also no greater than 
five miles.

The intervening, low density block or blocks of water or wetlands are 
not included in the urban area.
5. Inclusion of Enclaves
    The Census Bureau will add enclaves (that is, nonqualifying area 
completely surrounded by area already qualified for inclusion as urban) 
within the urban area, provided that they are surrounded only by land 
area that qualified for inclusion in the urban area based on housing 
unit density criteria, and at least one of the following conditions is 
met:
    a. The area of the enclave must be less than five square miles.
    b. All area of the enclave is surrounded by territory that 
qualified for inclusion in the initial urban area core and is more than 
a straight-line distance of 1.5 miles from a land block that is not 
part of the urban area.
    Additional enclaves will be identified and included within the 
urban area if:
    a. The area of the enclave is less than five square miles,
    b. The enclave is surrounded by both land that qualified for 
inclusion in the urban area and water, and
    c. The length of the line of adjacency with the water is less than 
the length of the line of adjacency with the land.
6. Inclusion of Airports
    After all territory has been added to the urban area core via hop 
and jump connections, and enclaves, the Census Bureau will then add 
whole census blocks that approximate the territory of airports, 
provided at least one of the blocks that represent the airport is 
within a distance of 0.5 miles of the edge of qualifying urban 
territory. An airport qualifies for inclusion if it is currently 
functional and one of the following criteria (per the Federal Aviation 
Administration's (FAA) Air Carrier Activity Information System \9\) 
applies:
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    \9\ The annual passenger boarding data only includes primary, 
non-primary commercial service, and general aviation enplanements as 
defined and reported by the FAA Air Carrier Activity Information 
System.
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    a. It is a qualified cargo airport.
    b. It has an annual passenger enplanement of at least 2,500 in any 
year between 2011 and 2019.
7. Additional Nonresidential Urban Territory
    The Census Bureau will identify additional nonresidential urban-
related territory that is noncontiguous, yet near the urban area. The 
Census Bureau recognizes the existence of large commercial and/or 
industrial land uses that are separated from an urban area by a 
relatively thin ``green buffer,'' small amount of undeveloped 
territory, and/or a narrow census block required for tabulation (such 
as a water feature, offset boundary, road median, or area between a 
road and rail feature). The Census Bureau will review all groups of 
census blocks whose members qualify as urban via the impervious surface 
criteria set forth in Section 1.b, have a total area of at least 0.15 
square miles,\10\ and are within 0.25 miles of an urban area. A final 
review of these census blocks and surrounding territory \11\ will

[[Page 10242]]

determine whether to include this territory in an urban area.
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    \10\ The Census Bureau found in testing that individual (or 
groups of) census blocks with a high degree of impervious surface 
land cover with an area less than 0.15 square miles tend to be more 
associated with road infrastructure features such as cloverleaf 
overpasses and multilane highways.
    \11\ Additional census blocks within eighty feet of the initial 
groups also qualifying as impervious, but failing the shape index, 
are also identified for review.
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8. Splitting Large Agglomerations and Merging Individual Urban Areas
    Population growth and redistribution coupled with the automated 
urban area delineation methodology that will be used for the 2020 
Census may result in large agglomerations of continuously developed 
territory that may encompass territory defined as separate urban areas 
for the 2010 Census. If such results occur, the Census Bureau will 
apply split and merge criteria.
    For the 2020 Census, the Census Bureau proposes using worker flow 
data (i.e., commuting flows) from the Longitudinal Employer-Household 
Dynamics (LEHD) Program to identify whether the agglomeration 
represents a single functionally integrated region or whether commuting 
patterns indicate the presence of distinct urban areas within the 
larger agglomeration. An agglomeration that encompasses two or more 
2010 Census urban areas will be a candidate for splitting into smaller 
urban areas. This condition will trigger application of the following 
splitting criteria:
    a. Each pair of 2010 Census urban areas will be analyzed to 
determine whether to split or to remain merged. The 2010 urban area 
with the smaller population will be analyzed in relation to the 2010 
urban area with the larger population.
    b. The 2010 Census urban area with the smaller population will 
remain in the agglomeration if at least 50 percent of its resident 
workers are employed within the larger 2010 Census urban area and at 
least 50 percent of the jobs in the smaller urban area are filled by 
workers residing within the larger 2010 Census urban area. If either of 
these conditions are not met, the smaller urban area will be split from 
the agglomeration and categorized based on the worker flow data.
    c. The 2010 Census urban areas are organized into four categories:
    1. Worker flows are 50 percent or more to or from another 2010 
Census urban area, but not in both directions;
    2. Worker flows are less than 50 percent internal, but also less 
than 50 percent with any other single 2010 Census urban area;
    3. Adjacent 2010 Census urban areas that are in categories 1 or 2;
    4. Worker flows are 50 percent or more internal to the 2010 Census 
urban area.
    d. Community detection is performed on the LEHD worker flow data 
using the Leiden Algorithm to identify commuter-based communities. The 
resulting communities are used to adjust the 2010 Census urban area 
split boundaries based on thresholds set to each of the four 
categories. However, for all categories, at least 50 percent of the 
worker flow must be internal to all resulting urban areas. The boundary 
between two urban areas may also be modified to avoid splitting an 
incorporated place, CDP, or minor civil division (MCD) between two 
urban areas at the time of delineation.
    e. Upon running the community detection algorithm, the resulting 
communities are used to adjust the 2010 Census urban area split 
boundaries, and to identify the potential boundary between the 
resulting 2020 urban areas, starting with urban areas in the first 
category (below) and progressing to the fourth category (below).
     Category 1. For the smaller of each urban area pair, 
adjacent communities (identified by the Leiden Algorithm) are added 
from the larger urban area until the internal worker flow of the 
smaller urban area is greater than 50 percent. Communities can only be 
added to the smaller urban area until the total housing unit count 
increases by less than 50 percent.
     Category 2. For the smaller of each urban area pair, 
adjacent communities (identified by the Leiden Algorithm) are added 
from the larger urban area until the internal worker flow is greater 
than 50 percent.
     Category 3. If there is greater than 10 percent worker 
flow between adjacent urban areas in categories 1 and 2, then they will 
be combined as one urban area and the criteria of the lowest category 
will be applied.
     Category 4. Split boundaries will be adjusted to their 
nearest community boundary.
9. Assigning Urban Area Titles
    A clear, unambiguous title based on commonly recognized place names 
helps provide context for data users and ensures that the general 
location and setting of the urban area can be clearly identified and 
understood. The title of an urban area identifies the place(s) that is 
(are) the most populated within the urban area. All population 
requirements for places and MCDs apply to the portion of the entity's 
population that is within the specific urban area being named. The 
Census Bureau proposes the following criteria to determine the title of 
an urban area:
    a. The most populous incorporated place within the urban area that 
has a population of 10,000 or more will be listed first in the urban 
area title.
    b. If there is no incorporated place with a population of 10,000 or 
more, the urban area title will include the name of the most populous 
incorporated place or CDP within the urban area that has at least 2,500 
people.
    c. Up to two additional places, in descending order of population 
size, may be included in the title of an urban area, provided that the 
place meets one of the following criteria:
    a. The place has 250,000 or more people.
    b. The place has at least 2,500 people, and that population is at 
least two-thirds of the urban area population of the most populous 
place in the urban area.
    If the urban area does not contain a place of at least 2,500 
people, the Census Bureau will consider the name of the incorporated 
place, CDP, or MCD with the largest total population in the urban area, 
or a local name recognized for the area by the United States Geological 
Survey's (USGS) Geographic Names Information System (GNIS), with 
preference given to names also recognized by the United States Postal 
Service (USPS). The urban area title will include the USPS abbreviation 
of the name of each state or statistically equivalent entity in which 
the urban area is located or extends. The order of the state 
abbreviations is the same as the order of the related place names in 
the urban area title.\12\
---------------------------------------------------------------------------

    \12\ In situations where an urban area is only associated with 
one place name but is located in more than one state, the order of 
the state abbreviations will begin with the state within which the 
place is located and continue in descending order of population of 
each state's share of the population of the urban area.
---------------------------------------------------------------------------

    If a single place or MCD qualifies as the title of more than one 
urban area, the largest urban area will use the name of the place or 
MCD. The smaller urban area will have a title consisting of the place 
or MCD name and the direction (North, South, East, or West) of the 
smaller urban area as it relates geographically to the larger urban 
area with the same place or MCD name.
    If any title of an urban area duplicates the title of another urban 
area within the same state, or uses the name of an incorporated place, 
CDP, or MCD that is duplicated within a state, the name of the county 
that has most of the population of the largest place or MCD is 
appended, in parentheses, after the duplicate place or MCD name for 
each urban area. If there is no incorporated place, CDP, or MCD name in 
the urban area title, the name of the county having the largest total 
population residing in the urban area will be appended to the title.

[[Page 10243]]

C. Definitions of Key Terms

    Census Block: A geographic area bounded by visible and/or invisible 
features shown on a map prepared by the Census Bureau. A census block 
is the smallest geographic entity for which the Census Bureau tabulates 
decennial census data.
    Census Designated Place (CDP): A statistical geographic entity 
encompassing a concentration of population, housing, and commercial 
structures that is clearly identifiable by a single name, but is not 
within an incorporated place. CDPs are the statistical counterparts of 
incorporated places for distinct unincorporated communities.
    Census Tract: A small, relatively permanent statistical geographic 
subdivision of a county or county equivalent defined for the tabulation 
and publication of Census Bureau data. The primary goal of the census 
tract program is to provide a set of nationally consistent small, 
statistical geographic units, with stable boundaries that facilitate 
analysis of data across time.
    Contiguous: Refers to two or more areas sharing common boundaries.
    Core Based Statistical Area (CBSA): A statistical geographic entity 
defined by the U.S. Office of Management and Budget, consisting of the 
county or counties or equivalent entities associated with at least one 
core of at least 10,000 population, plus adjacent counties having a 
high degree of social and economic integration with the core as 
measured through commuting ties with the counties containing the core. 
Metropolitan and micropolitan statistical areas are the two types of 
core based statistical areas.
    Enclave: An area with population or housing unit density lower than 
the minimum for qualification that is completely surrounded by area 
already qualified for inclusion as urban.
    Exempted Territory: Pre-existing land cover that offsets the 
pattern of urban development.
    Group Quarters (GQs): 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. 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. This is not a typical household-type living 
arrangement. People living in GQs are usually not related to each 
other. GQs include such facilities as college residence halls, 
residential treatment centers, skilled nursing facilities, group homes, 
military barracks, correctional facilities, and workers' dormitories.
    Impervious Surface: Paved, man-made surfaces, such as roads, 
parking lots, and rooftops.
    Indentation: Areas that are partially enveloped by, and likely to 
be affected by and integrated with, an already qualified urban 
territory.
    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 specific governmental services for a concentration 
of people within legally prescribed boundaries.
    Metropolitan Statistical Area: A core based statistical area 
associated with at least one urban area that has a population of at 
least 50,000. The metropolitan statistical area comprises the central 
county or counties or equivalent entities containing the core, plus 
adjacent outlying counties having a high degree of social and economic 
integration with the central county or counties as measured through 
commuting.
    Micropolitan Statistical Area: A core based statistical area 
associated with at least one urban area that has a population of at 
least 10,000, but less than 50,000. The micropolitan statistical area 
comprises the central county or counties or equivalent entities 
containing the core, plus adjacent outlying counties having a high 
degree of social and economic integration with the central county or 
counties as measured through commuting.
    Minor Civil Division (MCD): The primary governmental or 
administrative division of a county or equivalent entity in 29 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.
    New England City and Town Area (NECTA): A statistical geographic 
entity that is delineated by the U.S. Office of Management and Budget 
based on county subdivisions--usually cities and towns. NECTAs are 
defined using the same criteria as county-based CBSAs, and, similar to 
CBSAs, NECTAs are categorized as metropolitan or micropolitan.
    Noncontiguous: Two or more areas that do not share common 
boundaries, such that the areas are separated by intervening territory.
    Rural: Territory not defined as urban.
    Topologically Integrated Geographic Encoding and Referencing 
(TIGER): 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.
    Urban: Generally, densely developed territory, encompassing 
residential, commercial, and other non-residential urban land uses 
within which social and economic interactions occur.
    Urban Area Core: Continuous area qualified as urban prior to the 
application of the hop and jump criteria.
    Urban Cluster: A statistical geographic entity consisting of a 
densely settled core created from census tracts or blocks and 
contiguous qualifying territory that together have at least 2,500 
persons but fewer than 50,000 persons.
    Urbanized Area: A statistical geographic entity consisting of a 
densely settled core created from census tracts or blocks and adjacent 
densely settled territory that together have a minimum population of 
50,000 people.
    Ron S. Jarmin, Acting Director, Bureau of the Census, approved the 
publication of this Notice in the Federal Register.

    Authority: Title 13, U.S.C., Chapter V.

    Dated: February 16, 2021.
Sheleen Dumas,
Department PRA Clearance Officer, Office of the Chief Information 
Officer, Commerce Department.
[FR Doc. 2021-03412 Filed 2-18-21; 8:45 am]
BILLING CODE 3510-07-P