Proposed Urban Area Criteria for the 2010 Census, 52174-52184 [2010-20808]

Agencies

• DEPARTMENT OF COMMERCE
• Bureau of the Census
• Census Bureau

[Federal Register Volume 75, Number 163 (Tuesday, August 24, 2010)]
[Notices]
[Pages 52174-52184]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-20808]



[[Page 52173]]

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Part IV





Department of Commerce





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Bureau of the Census



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Proposed Urban Area Criteria for the 2010 Census; Notice

Federal Register / Vol. 75 , No. 163 / Tuesday, August 24, 2010 / 
Notices

[[Page 52174]]


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DEPARTMENT OF COMMERCE

Bureau of the Census

[Docket Number 100701026-0260-02]


Proposed Urban Area Criteria for the 2010 Census

AGENCY: Bureau of the Census, Department of Commerce.

ACTION: Notice of proposed criteria and request for public comment.

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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 2010 Decennial Census (the term ``urban area'' as 
used throughout this notice refers generically to urbanized areas of 
50,000 or more population and urban clusters of at least 2,500 and less 
than 50,000 population). It also provides a description of the changes 
from the final criteria used for Census 2000. The Census Bureau is 
requesting public comment on these proposed criteria.
    The Census Bureau's urban-rural classification is fundamentally a 
delineation of geographical areas, identifying both individual urban 
areas and the rural areas 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 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. The revisions over the years 
reflect the Census Bureau's desire to improve the classification of 
urban and rural territory to take advantage of newly available data, as 
well as advancements in geographic information processing technology.

DATES: Any comments, suggestions, or recommendations concerning the 
criteria proposed herein should be submitted in writing no later than 
November 22, 2010.

ADDRESSES: Please submit written comments on the proposed criteria to 
Timothy Trainor, Chief, Geography Division, U.S. Census Bureau, 
Washington, DC 20233-7400.

FOR FURTHER INFORMATION CONTACT: Vincent Osier, Chief, Geographic 
Standards and Criteria Branch, Geography Division, U.S. Census Bureau, 
via e-mail at vincent.osier@census.gov or telephone at 301-763-9039.

SUPPLEMENTARY INFORMATION: The Census Bureau's urban-rural 
classification is fundamentally a delineation of geographical areas, 
identifying both individual urban areas and the rural areas 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 this ``urban footprint'' 
have been defined using measures based primarily on population counts 
and residential population density, but also through 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 densely settled urbanized areas 
(UAs) of 50,000 or more people were first defined, 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 and rural 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-rural classification for 
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.
    The Census Bureau is not responsible for the use of its urban-rural 
classification in nonstatistical programs. If a federal, tribal, state, 
or local agency voluntarily uses the urban-rural classification in a 
nonstatistical program, it is that agency's responsibility to ensure 
that the classification is appropriate for such use. In considering the 
appropriateness of the classification for use in a nonstatistical 
program, the Census Bureau urges each agency to consider permitting 
appropriate modifications of the results of implementing the urban-
rural classification specifically for the purposes of its program. When 
a program permits such modifications, the Census Bureau urges each 
agency to describe and clearly identify the different criteria being 
applied to avoid confusion with the Census Bureau's official urban-
rural classifications.

I. History

    Over the course of a century in defining urban areas, the Census 
Bureau has introduced conceptual and methodological changes to ensure 
that the urban-rural 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, 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 UA 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. Due to the limitations in 
technology for calculating and mapping population density, delineation 
of UAs was limited to cities of at least 50,000 people and their 
surrounding territory. The geographic units used to analyze settlement 
patterns were enumeration districts, but to facilitate and ease the 
delineation process, each incorporated place was analyzed as a single 
unit--that is, the overall density of the place was calculated and if 
it met the minimum threshold, it was included in its entirety in the 
UA. Outside UAs, ``urban'' was still defined as any place with a 
population of at least 2,500. The Census Bureau recognized the need to 
identify distinct unincorporated communities existing outside the UAs, 
and thus created the ``census designated place'' (CDP) \1\ and 
designated those with populations of at least 2,500 as urban.
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    \1\ A CDP is 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.

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[[Page 52175]]

    Starting with the 1960 Census and continuing through the 1990 
Census, the Census Bureau made a number of changes to the methodology 
and criteria for defining UAs, but retained the 1950 Census basic 
definition of ``urban,'' which was defined as UAs with a population of 
50,000 or more and defined primarily on the basis of population 
density; and places with a population of 2,500 or more located outside 
UAs. The enhancements made by the Census Bureau to the methodology and 
criteria used during this period included:
    (1) Lowering, and eventual elimination, of minimum population 
criteria for places that formed the ``starting point'' for delineating 
a UA. This made recognition of population concentrations independent of 
the size of any single place within the concentration.
    (2) Identification of ``extended cities''--incorporated places 
containing substantial amounts of territory with very low population 
density, which were divided into urban and rural components using 100 
persons per square mile (ppsm) as the criterion. This kept the extent 
of urban territory from being artificially exaggerated by thinly 
settled corporate annexations.
    (3) Implementation for the 1990 Census of nationwide coverage by 
census blocks, and use of interactive analysis of population density 
patterns at the census block level, or by groups of blocks known as 
``analysis units,'' using Census Bureau-developed delineation software. 
This enhancement allowed greater flexibility when analyzing and 
defining potential UAs, as opposed to using enumeration districts and 
other measurement units defined prior to data tabulation.
    (4) Implementation of qualification criteria for incorporated 
places and CDPs for inclusion in a UA based on the existence of a 
densely populated ``core'' containing at least fifty percent of the 
place's population. This eliminated certain places from the urban area 
classification because much of their population was scattered rather 
than concentrated.
    For Census 2000, the Census Bureau took advantage of technological 
advances associated with geographic information systems (GIS) and 
spatial data processing to classify urban and rural territory on a more 
consistent and nationally uniform basis than had been possible 
previously. Rather than delineating urban areas in an interactive and 
manual fashion, the Census Bureau developed and utilized software that 
automated the examination of population densities and other aspects of 
the criteria to delineate urban areas. This new automated urban area 
delineation methodology provided for a more objective application of 
criteria compared to previous censuses in which individual geographers 
applied the urban area criteria to delineate urban areas interactively. 
This new automated approach also established a baseline for future 
delineations to enable the Census Bureau to provide comparable data for 
subsequent decades.

Changes for Census 2000

    The Census Bureau adopted six substantial changes to its urban area 
criteria for Census 2000:
    (1) Defining urban clusters (UCs). Beginning with Census 2000, the 
Census Bureau created and implemented the concept of an urban cluster. 
Urban clusters are defined as areas of at least 2,500 and less than 
50,000 people using the same residential population density-based 
criteria as applied to UAs. This change provided for a conceptually 
consistent, seamless classification of urban territory. For previous 
censuses, the lack of a density-based approach for defining urban areas 
of less than 50,000 people resulted in underbounding of urban areas 
where densely settled populations existed outside place boundaries or 
overbounding when cities annexed territory with low population density. 
Areas where annexation had lagged behind expansion of densely settled 
territory, or where communities of 2,500 up to 50,000 people were not 
incorporated and were not defined as CDPs, were most affected by the 
adoption of density-based UCs. As a result of this change, the Census 
Bureau no longer needed to identify urban places located outside UAs 
for the purpose of its urban-rural classification.
    (2) Disregarding incorporated place and CDP boundaries when 
defining UAs and UCs. Taking place boundaries into account in previous 
decades resulted in the inclusion of territory with low population 
density within UAs when the place as a whole met minimum population 
density requirements, and excluded densely settled population when the 
place as a whole fell below minimum density requirements. 
Implementation of this change meant that territory with low population 
density located inside place boundaries (perhaps due to annexation, or 
the way in which a CDP was defined) no longer necessarily qualified for 
inclusion in an urban area. However, it also meant that non-residential 
urban land uses located inside a place's boundary and located on the 
edge of an urban area might not necessarily qualify to be included in a 
UA or UC.
    (3) Adoption of 500 persons per square mile (ppsm) as the density 
criterion for recognizing some types of urban territory. The Census 
Bureau adopted a 500 ppsm population density threshold at the same time 
that it adopted its automated urban area delineation methodology. This 
ensured that census blocks that might contain a mix of residential and 
non-residential urban uses, but might not have a population density of 
at least 1,000 ppsm, could qualify for inclusion in an urban area. For 
the 1990 Census, geographers could interactively modify analysis units 
to include census blocks with low population density that might contain 
non-residential urban uses, while still achieving an overall population 
density of at least 1,000 ppsm. Adoption of the lower density threshold 
facilitated use of the automated urban area delineation methodology, 
and provided for comparability with the 1990 methodology. This change 
did not result in substantial increases to the extent of urban areas.
    (4) Increase in the jump distance from 1.5 to 2.5 miles. The Census 
Bureau increased the jump distance from 1.5 to 2.5 miles. A ``jump'' is 
the distance across territory with low population density separating 
noncontiguous qualifying territory from the main body of an urban area. 
The increase in the jump distance was a result of changing planning 
practices that led to the creation of larger clusters of single-use 
development. In addition, research conducted prior to Census 2000 
showed that some jumps incorporated in UA definitions in 1990 were 
actually longer than 1.5 miles as a result of the subjective 
identification of undevelopable territory. As used in previous 
censuses, only one jump was permitted along any given road connection.
    (5) Introduction of the hop concept to provide an objective basis 
for recognizing small gaps within qualifying urban territory. For 
Census 2000, the Census Bureau officially recognized the term ``hops,'' 
which is defined as gaps of 0.5 miles or less within a qualifying urban 
territory. Hops are used primarily to account for territory in which 
planning and zoning processes result in alternating patterns of 
residential and non-residential development over relatively short 
distances. This provided for a more consistent treatment of short gaps 
with low population density, some of which had been treated as jumps in 
the 1990 urban area delineation process (and not

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permitted if identified as a second jump), while others were 
interpreted as part of the pattern of urban development and grouped 
with adjacent, higher density blocks to form qualifying analysis units.
    (6) Adoption of a zero-based approach to defining urban areas. The 
urban area delineation process in previous censuses had generally been 
an additive process, where the boundary of a UA from the previous 
census providing the starting point for review for the next census. The 
changes made for Census 2000 were substantial enough to warrant the 
Census Bureau to re-evaluate the delineation of all urban areas as if 
for the first time, rather than simply making adjustments to the 
existing boundary. The Census Bureau adopted this zero-based approach 
to ensure that all urban areas were defined in a consistent manner.
    The six changes described above represent the major modifications 
implemented for the 2000 Census. They illustrate the substantial shift 
in approach adopted by the Census Bureau in its procedure for 
delineating urban areas. However, the availability of new datasets and 
continued research since the 2000 Census show the potential for further 
improvements for the 2010 Census.

II. Differences Between the Proposed 2010 Census Urban Area Criteria 
and the Census 2000 Urban Area Criteria

    For the 2010 Census, the Census Bureau proposes 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. The proposed changes and 
enhancements recognize that the Census Bureau's urban-rural 
classification provides an important national baseline definition of 
urban and rural areas.
    The following summary describes the differences between the Census 
2000 urban area criteria and the urban area criteria proposed for the 
2010 Census.

Use of Census Tracts as Analysis Units in the Initial Phase of 
Delineation

    For the Census 2000 urban area delineation process, the Census 
Bureau used blocks and block groups as analysis units (geographic 
building blocks). For the 2010 Census delineation process, the Census 
Bureau proposes replacing block groups with census tracts as the 
analysis unit during the delineation of the initial urban area core. 
Similar to the way block groups were used in 2000, if a census tract 
does not meet specified proposed area measurement and density criteria, 
the focus of analysis will shift to individual census blocks within the 
tract, and delineation will continue at the block level. During the 
initial urban area core delineation (see section B.1 in the proposed 
urban area criteria below for a description of an initial urban area 
core), the maximum size threshold for qualifying census tracts will be 
three square miles compared to the two square mile threshold adopted 
for block groups for Census 2000 (Figure 1). Changing the urban area 
core delineation analysis unit to the census tract offers advantages of 
increased consistency and comparability, since census tracts are more 
likely to retain their boundaries over time than block groups.
[GRAPHIC] [TIFF OMITTED] TN24AU10.015

    Although census tracts will be used in the delineation of initial 
urban area cores, as in Census 2000 census blocks will continue to form 
the analysis units when analyzing territory beyond the qualifying 
tracts, for example on the edge of the urban area or when including 
noncontiguous territory via hops and jumps.
    Test delineations of initial cores in selected areas of the United 
States

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(Figure 2) show slight decreases in territory and only slight increases 
in population qualifying as urban when the initial analysis unit is 
changed from the block group to the census tract.\2\
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    \2\ Two initial core test delineations were performed for eight 
test delineation regions covering an area of approximately 392,900 
square miles. The first initial core test delineation used the same 
population count, population density, geographic area, and proximity 
criteria used for the Census 2000 urban area delineation. The second 
test used the proposed criteria for the same items, but also 
reflected the 2010 Census proposed use of census tracts in the 
identification of initial cores. Both tests used Census 2000 
population counts and geography and implemented the impervious 
surface and enclave criteria proposed for the 2010 Census in this 
notice.
[GRAPHIC] [TIFF OMITTED] TN24AU10.016

    Table 1 provides a comparison of the number of cores defined using 
block groups as analysis units with the number defined using census 
tracts. Population, land area, and population density for the cores 
also are provided for comparison.

  Table 1--Comparison of Initial Urban Area Cores Defined Using Block Groups or Census Tracts as Analysis Units
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                                                                                                    Population
                                                     Number of    Population  in     Land area        density
                                                       cores      cores  (Census    (sq. miles)     (people per
                                                                       2000)                       square mile)
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Block group as analysis unit when defining cores             904      42,213,521          15,027           2,809
Census tract as analysis unit when defining                  924      42,384,952          14,525           2,918
 cores..........................................
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    The small reduction in initial urban area core territory shown by 
the test data is due to the use of census tracts, which are larger 
geographic units, and therefore less likely than block groups to 
qualify under the density requirements. As a result, when using census 
tracts, the delineation process shifts to census block-level analysis 
sooner than would be the case when using block groups.

Maximum Distances of Jumps

    The Census Bureau is considering reducing the maximum jump distance 
to 1.5 miles based on data users' comments that the 2.5 mile distance 
adopted for the 2000 Census was too generous in some situations and 
resulted in the overextension of urban area territory. The Census 
Bureau seeks comment on whether the jump distance should revert to the 
1.5 mile maximum that was in use from 1950 through 1990.

Use of Land Use/Land Cover Data

    The Census Bureau plans to use the newly available National Land 
Cover Database (NLCD) developed by the Multi-Resolution Land 
Characteristics Consortium to identify business districts and 
commercial zones, located both on

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the edge and in the interior of an urban area that would not qualify as 
urban based on residential population measures alone. The NLCD is a 
consistently defined national land cover dataset \3\ that would enable 
the Census Bureau to add further territory to the list of exempted 
territory and enforce its qualification criteria objectively (Figure 
3). This nationwide dataset will assist the Census Bureau in 
identifying, and qualifying as urban, sparsely populated urban-related 
territory associated with a high degree of impervious surface land 
cover. It also will assist the Census Bureau to identify land cover 
types that restrict development, such as marshes, wetlands, and 
estuaries, which will be included as exempted territory. Without such 
recognition, these types of undevelopable land covers would otherwise 
prohibit two or more communities to connect via a jump, even though 
they share functional ties.
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    \3\ The NLCD includes data for the entirety of the United 
States, Puerto Rico, and the U.S. Virgin Islands.
[GRAPHIC] [TIFF OMITTED] TN24AU10.017

Qualification of Airports for Inclusion in Urban Areas

    For Census 2000, airports with an annual enplanement (departing 
passengers) of 10,000 or greater qualified for inclusion in an urban 
area if adjacent to other qualifying territory. For the 2010 Census, 
the Census Bureau proposes lowering the minimum annual enplanement 
threshold to 2,500 passengers to provide a better inclusion of 
airports, particularly those adjacent to smaller initial urban cores. 
Based on annual passenger boarding and all-cargo data published by the 
Federal Aviation Administration for the 2007 calendar year, lowering 
the enplanement threshold would result in an additional 152 airports 
included in urban areas.\4\
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    \4\ The Federal Aviation Administration (FAA) annual passenger 
boarding and all-cargo data extracted from the Air Carrier Activity 
Information System published for the 2007 calendar year reports 409 
airports had an annual enplanement of at least 10,000 passengers in 
any year between 2000 and 2007.
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Elimination of the Central Place Concept

    The Census Bureau proposes to discontinue identifying central 
places as part of the 2010 Census urban area delineation process. A 
central place is the most populous place within an urban area or any 
other place that meets specified population criteria. Starting with the 
1990 Census, the identification of central places was no longer 
necessary for the process of delineating urban areas. For Census 2000, 
the urban area delineation process moved away from a ``place-based'' 
definition of urban areas, which caused some central places to be split 
between urban and rural territory. Moreover, the Office of Management 
and Budget (OMB) identifies principal cities as part of the 
metropolitan and micropolitan statistical areas program.\5\ The list of 
principal cities identified by the OMB is quite similar to what would 
emerge if the urban area process created a list of central places. The 
Census Bureau no longer sees a need for a second representation of the 
same concept in its statistical and geographic data products. 
Therefore, the Census Bureau proposes to eliminate the use of central 
places in the 2010 Census urban area delineation criteria.
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    \5\ See the ``2010 Standards for Delineating Metropolitan and 
Micropolitan Statistical Areas,'' Federal Register, Vol. 75, No. 
123, Monday, June 28, 2010.
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Requirement for Minimum Population Residing Outside Institutional Group 
Quarters

    The Census 2000 urban area delineation criteria resulted in the 
identification of 24 urban clusters consisting entirely or 
predominantly of

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population residing in institutional group quarters (GQs). Most of 
these urban clusters comprised only the few census blocks in which the 
institutional GQ was located. These blocks met the population density 
requirements specified in the Census 2000 criteria, and encompassed at 
least 2,500 persons. Although the population densities of these areas 
exceed the minimum thresholds specified in the Census 2000 urban area 
criteria, and the total populations exceed 2,500, they lack most of the 
residential, commercial, and infrastructure characteristics typically 
associated with urban territory. The Census Bureau proposes that in 
addition to at least 2,500 total population, an area must contain at 
least 1,500 persons who reside outside institutional GQs to qualify as 
urban.

Splitting Large Urban Agglomerations

    Similar to the delineation process used for the 2000 Census, the 
Census Bureau will use the same automated urban area delineation 
methodology for determining urban and rural areas in the 2010 Census. 
Use of this approach will result in some exceptionally large urban 
agglomerations of continuously developed territory. Although such areas 
do reflect the reality of urbanization at one scale, the areas may be 
cumbersome and less satisfactory for more localized applications. For 
example, an area of virtually continuous urbanization exists from 
northeastern Maryland through the Philadelphia area, central New 
Jersey, the New York City area, and central Connecticut to beyond 
Springfield, MA. This area of near-continuous urbanization encompasses 
nine UAs defined for Census 2000. Another area of continuous 
urbanization exists in the San Francisco Bay area, including the San 
Francisco-Oakland, San Jose, and several smaller areas.
    The Census Bureau anticipates that many data users would find these 
large agglomerations to be inconvenient for meaningful analysis, and 
therefore, proposes that they be split in some consistent fashion. For 
example, the Census Bureau split large agglomerations for Census 2000 
by using metropolitan statistical area and primary metropolitan 
statistical area (PMSA) boundaries as a guide to identify the narrowest 
area along the high density ``corridor'' between larger core areas. For 
instance, the corridor of high residential population density between 
Baltimore, MD, and Washington, DC, was narrowest in northern Prince 
George's County, MD, in the area of Beltsville, MD, and near the 
boundary between the Washington PMSA and the Baltimore PMSA.
    For the 2010 Census urban area delineation process, the Census 
Bureau proposes splitting large agglomerations along metropolitan 
statistical area boundaries, resulting in the identification of 
individual UAs. In New England, large agglomerations would be split 
based on the boundaries of metropolitan New England city and town areas 
(NECTAs). In areas where an incorporated place or a CDP crosses the 
metropolitan statistical area or NECTA boundary, the boundary splitting 
the large agglomeration would be modified to follow the incorporated 
place or CDP boundary. The incorporated place or CDP would be assigned 
to the resulting UA that contains the largest proportion of the place's 
land area (Figure 4). Urban clusters would not be created as a result 
of splitting.
[GRAPHIC] [TIFF OMITTED] TN24AU10.018

    This approach has the advantage of simplicity and ease of 
implementation. It also maintains some comparability with previous 
decades' criteria and definitions. This approach, however, results in 
some circularity of outcomes--the metropolitan statistical area and 
NECTA definitions that would be used to split large agglomerations are

[[Page 52180]]

those that were defined on the basis of Census 2000 data, including 
Census 2000 urban area definitions; the 2010 UAs resulting from the 
splitting process will form the cores of metropolitan statistical areas 
and NECTAs. In addition, this approach will result in the movement of 
some territory and population from one UA to another. For example, the 
split between the Washington and Baltimore UAs would occur along the 
Howard County, MD-Prince George's County, MD boundary; territory in 
northern Prince George's County, MD that currently is in the Baltimore 
UA would be included in the Washington UA. The split between the San 
Francisco-Oakland and San Jose UAs would shift northward to follow the 
San Mateo County, CA-Santa Clara County, CA boundary.
    Based on Census 2000 UAs, the Census Bureau has identified 52 
potential agglomerations consisting of multiple and currently separate 
UAs. These agglomerations contain UAs that currently are contiguous as 
well as some that are in close proximity to each other and that 
potentially could form a continuous agglomeration when areas are 
redefined based on 2010 Census data (note, however, that inclusion in 
the list below does not necessarily mean that contiguity will exist 
between two UAs when redefined). The following table lists the 
potential agglomerations, the component UAs, and the estimated 
population based on the 2006-2008 ACS 3-year estimates (margins of 
error are not noted in the table below; 3-year estimates were used 
because not all UAs met the 65,000 person threshold for ACS 1-year 
estimates). The Census Bureau is considering applying a 1,000,000 
person minimum population threshold to identify agglomerations to be 
split, but seeks comment on the appropriate population size threshold 
to determine which large agglomerations would be split. Other minimum 
population thresholds under consideration are 500,000 and 250,000. 
Based on 2006-2008 ACS estimates, 27 of the 52 potential agglomerations 
have populations less than 1,000,000; 14 have populations less than 
500,000; and four have populations less than 250,000. If a threshold of 
1,000,000 people is chosen as the minimum for splitting large 
agglomerations, all formerly separate UAs in agglomerations of less 
than 1,000,000 people would be merged to form a single UA. If 500,000 
people is adopted as the minimum threshold, then all formerly separate 
UAs in agglomerations of less than that threshold would be merged. 
Because UAs form the cores of metropolitan statistical areas, the 
merger of formerly separate UAs might affect the delineation of 
metropolitan and micropolitan statistical areas. It is important to 
note that some of the agglomerations listed below are contained within 
the same metropolitan statistical area, and as a result, would not be 
split, regardless of the threshold chosen. The agglomerations are: 
Dallas-Fort Worth; Houston-Texas City; Phoenix-Mesa; San Diego-Mission 
Viejo; St. Louis-Alton; Pittsburgh-Uniontown-Monessen; Kansas City-
Lee's Summit; Charlotte-Gastonia-Concord; Nashville-Murfreesboro; 
Oklahoma City-Norman; Honolulu-Kailua; Stockton-Lodi-Manteca; Boise 
City-Nampa; Modesto-Turlock; Santa Rosa-Petaluma; Beaumont-Port Arthur; 
and Fairfield-Vacaville.

                                     Table 2--Potential Urban Agglomerations
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                                                                                                   2006-2008 ACS
         Potential urban agglomeration           Census 2000 UAs contained within the potential       3-year
                                                                  agglomeration                      estimated
----------------------------------------------------------------------------------------------------population--
New York-Philadelphia-Connecticut.............  New York-Newark, NY-NJ-CT; Philadelphia, PA-NJ-       29,028,337
                                                 DE-MD; Allentown-Bethlehem, PA-NJ; Lancaster,
                                                 PA; Pottstown, PA; Reading, PA; Trenton, NJ;
                                                 Hightstown, NJ; Vineland, NJ; Poughkeepsie-
                                                 Newburgh, NY; Bridgeport-Stamford, CT; Danbury,
                                                 CT-NY; Hartford, CT; New Haven, CT; Norwich-New
                                                 London, CT; Waterbury, CT; Springfield, MA-CT.
Los Angeles-Riverside-San Bernardino..........  Los Angeles-Long Beach-Santa Ana, CA; Riverside-      15,492,749
                                                 San Bernardino, CA; Camarillo, CA; Hemet, CA;
                                                 Oxnard, CA; Santa Barbara, CA; Santa Clarita,
                                                 CA; Simi Valley, CA; Temecula-Murrieta, CA;
                                                 Thousand Oaks, CA.
Chicago-Kenosha-Racine-Round Lake Beach.......  Chicago, IL-IN; Kenosha, WI; Round Lake Beach-         8,944,789
                                                 McHenry-Grayslake, IL-WI; Racine, WI.
Boston-Providence-Worcester...................  Boston, MA; Providence, RI-MA; Worcester, MA-CT;       6,692,295
                                                 Barnstable Town, MA; Leominster-Fitchburg, MA;
                                                 New Bedford, MA; Dover-Rochester, NH;
                                                 Manchester, NH; Nashua, NH; Portsmouth, NH.
Baltimore-Washington..........................  Aberdeen, MD; Baltimore, MD; Washington, DC-VA-        6,585,315
                                                 MD; St. Charles, MD.
San Francisco-Oakland-San Jose................  San Francisco-Oakland, CA; San Jose, CA;               5,870,212
                                                 Antioch, CA; Concord, CA; Livermore, CA;
                                                 Vallejo, CA.
Dallas-Fort Worth.............................  Dallas-Fort Worth-Arlington, TX; Denton-               5,006,527
                                                 Lewisville, TX; McKinney, TX.
Houston-Texas City............................  Houston, TX; Texas City, TX; Galveston, TX; The        4,599,176
                                                 Woodlands, TX.
Detroit-Ann Arbor-Port Huron..................  Detroit, MI; Ann Arbor, MI; Port Huron, MI;            4,326,040
                                                 South Lyon-Howell-Brighton, MI.
Atlanta-Gainesville...........................  Atlanta, GA; Gainesville, GA....................       4,196,670
San Juan-Aguadilla-Ponce......................  San Juan, PR; Aguadilla-Isabela-San                    3,591,491
                                                 Sebasti[aacute]n, PR; Arecibo, PR; Fajardo, PR;
                                                 Florida-Barceloneta-Bajadero, PR; Guayama, PR;
                                                 Juana D[iacute]az, PR; Mayag[uuml]ez, PR;
                                                 Ponce, PR; San Germ[aacute]n-Cabo Rojo-Sabana
                                                 Grande, PR; Yauco, PR.
Phoenix-Mesa-Avondale.........................  Phoenix-Mesa, AZ; Avondale, AZ..................       3,328,183
San Diego-Mission Viejo.......................  San Diego, CA; Mission Viejo, CA................       3,273,255
Seattle-Bremerton-Marysville..................  Seattle, WA; Bremerton, WA; Marysville, WA......       3,206,057
Cleveland-Akron-Canton-Lorain-Elyria..........  Cleveland, OH; Akron, OH; Canton, OH; Lorain-          2,722,194
                                                 Elyria, OH.
Tampa-St. Petersburg-Lakeland-Winter Haven....  Tampa-St. Petersburg, FL; Lakeland, FL; Winter         2,719,812
                                                 Haven, FL; Brooksville, FL.
Cincinnati-Dayton-Middletown..................  Cincinnati, OH-KY-IN; Dayton, OH; Middletown,          2,426,070
                                                 OH; Springfield, OH.
Denver-Boulder-Longmont.......................  Denver-Aurora, CO; Boulder, CO; Longmont, CO;          2,339,587
                                                 Lafayette-Louisville, CO.
St. Louis-Alton...............................  St. Louis, MO-IL; Alton, IL.....................       2,184,037

[[Page 52181]]

 
Orlando-Ocala-Kissimmee.......................  Orlando, FL; Ocala, FL; Kissimmee, FL; Lady            1,814,061
                                                 Lake, FL; Leesburg-Eustis, FL.
Pittsburgh-Uniontown-Monessen.................  Pittsburgh, PA; Uniontown-Connellsville, PA;           1,792,892
                                                 Monessen, PA.
Kansas City-Lee's Summit......................  Kansas City, MO-KS; Lee's Summit, MO............       1,468,106
Salt Lake City-Ogden-Layton...................  Salt Lake City, UT; Ogden-Layton, UT............       1,439,004
Indianapolis-Anderson.........................  Indianapolis, IN; Anderson, IN..................       1,367,392
Charlotte-Gastonia-Concord....................  Charlotte, NC-SC; Gastonia, NC; Concord, NC;           1,282,839
                                                 Rock Hill, SC.
Nashville-Murfreesboro........................  Nashville-Davidson, TN; Murfreesboro, TN........         983,180
Raleigh-Durham................................  Raleigh, NC; Durham, NC.........................         974,582
Palm Bay-Melbourne-Titusville-Vero Beach......  Palm Bay-Melbourne, FL; Titusville, FL; Vero             938,675
                                                 Beach-Sebastian, FL; Port St. Lucie, FL.
Oklahoma City-Norman..........................  Oklahoma City, OK; Norman, OK...................         875,469
Honolulu-Kailua (Honolulu County).............  Honolulu, HI; Kailua (Honolulu County), HI......         854,430
McAllen-Harlingen.............................  McAllen, TX; Harlingen, TX......................         753,816
Greensboro-High Point-Winston-Salem...........  Greensboro, NC; High Point, NC; Winston-Salem,           741,457
                                                 NC.
Sarasota-Bradenton-Punta Gorda................  Sarasota-Bradenton, FL; North Port-Punta Gorda,          726,695
                                                 FL.
Bonita Springs-Naples-Cape Coral..............  Bonita Springs-Naples, FL; Cape Coral, FL.......         659,480
Harrisburg-York-Lebanon.......................  Harrisburg, PA; York, PA; Lebanon, PA...........         651,160
Greenville-Spartanburg........................  Greenville, SC; Spartanburg, SC; Mauldin-                568,737
                                                 Simpsonville, SC.
Pensacola-Fort Walton Beach...................  Pensacola, FL-AL; Fort Walton Beach, FL.........         506,715
Stockton-Lodi-Manteca.........................  Stockton, CA; Lodi, CA; Manteca, CA.............         501,544
Spokane-Coeur d'Alene.........................  Spokane, WA-ID; Coeur d'Alene, ID...............         441,042
Boise City-Nampa..............................  Boise City, ID; Nampa, ID.......................         422,639
Modesto-Turlock...............................  Modesto, CA; Turlock, CA........................         414,571
South Bend-Elkhart............................  South Bend, IN-MI; Elkhart, IN-MI...............         408,373
Salinas-Santa Cruz-Watsonville................  Salinas, CA; Santa Cruz, CA; Watsonville, CA....         388,071
Charleston-Huntington.........................  Charleston, WV; Huntington, WV-KY-OH............         354,568
Santa Rosa-Petaluma...........................  Santa Rosa, CA; Petaluma, CA....................         351,752
Rockford-Beloit...............................  Rockford, IL; Beloit, WI-IL.....................         337,215
Atlantic City-Wildwood........................  Atlantic City, NJ; Wildwood-North Wildwood-Cape          280,698
                                                 May, NJ.
Appleton-Oshkosh..............................  Appleton, WI; Oshkosh, WI.......................         263,213
Beaumont-Port Arthur..........................  Beaumont, TX; Port Arthur, TX...................         249,716
Macon-Warner Robins...........................  Macon, GA; Warner Robins, GA....................         232,780
Kingsport-Johnson City........................  Kingsport, TN-VA; Johnson City, TN..............         208,241
Fairfield-Vacaville...........................  Fairfield, CA; Vacaville, CA....................         207,859
----------------------------------------------------------------------------------------------------------------

Proposed Urban Area Criteria for the 2010 Census

    The proposed criteria outlined herein apply to the United 
States,\6\ Puerto Rico, and the Island Areas.\7\ The Census Bureau 
proposes the following criteria and characteristics for use in 
identifying the areas that will qualify for designation as urbanized 
areas and urban clusters for use in tabulating data from the 2010 
Census, the American Community Survey (ACS), the Puerto Rico Community 
Survey, and potentially other Census Bureau censuses and surveys.
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    \6\ For Census Bureau purposes, the United States includes the 
50 States and the District of Columbia.
    \7\ For Census Bureau purposes, the Island Areas include 
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 are an aggregation of nine U.S. 
territories: Baker Island, Howland Island, Jarvis Island, Johnston 
Atoll, Kingman Reef, the Midway Islands, Navassa Island, Palmyra 
Atoll, and Wake Island.
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A. 2010 Census Urban Area, Urbanized Area, and Urban Cluster 
Definitions
    For the 2010 Census, an urban area will comprise a densely settled 
core of census tracts \8\ and/or census blocks \9\ that meet minimum 
population density requirements, along with adjacent territory 
containing non-residential urban land uses as well as territory with 
low population density 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 mentioned 
above must encompass at least 2,500 people, at least 1,500 of which 
reside outside institutional group quarters. Urban areas that contain 
50,000 or more people are designated as urbanized areas (UAs); urban 
areas that contain at least 2,500 and less than 50,000 people are 
designated as urban clusters (UCs). The term ``urban area'' refers to 
both UAs and UCs. The term ``rural'' encompasses all population, 
housing, and territory not included within an urban area.
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    \8\ A census tract is made up of from one to ten census block 
groups within a single county. A census block group is a collection 
of one to 999 census blocks within a single census tract.
    \9\ 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, MCD, county, or other 2010 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 within and partly 
outside an urban area. Any place that is split by an urban area 
boundary is referred to as an extended place. 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, population, and 
population density, 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

[[Page 52182]]

population density include only land; the areas of water contained 
within census tracts and census blocks are not used to calculate 
population density.
B. Proposed UA and UC Delineation Criteria
    The Census Bureau proposes to define urban areas primarily on the 
basis of residential population density measured at the census tract 
and census block levels of geography. Two population density thresholds 
are utilized in the delineation of urban areas: 1,000 ppsm and 500 
ppsm. The higher threshold is consistent with final population density 
criteria used in the 1960 through 1990 urban area delineation 
processes; it is used to identify the starting point for delineation of 
individual, potential urban areas and ensures that each urban area 
contains a densely settled core area that is consistent with previous 
decades' delineations. The lower threshold was adopted for the Census 
2000 process when the Census Bureau adopted an automated delineation 
methodology; it ensures that additional territory that may contain a 
mix of residential and non-residential urban uses can qualify for 
inclusion in an urban area.
1. Identification of Initial Urban Area Cores
    The Census Bureau proposes to begin the delineation process by 
identifying and aggregating contiguous census tracts, each having a 
land area less than three square miles and a population density of at 
least 1,000 ppsm. If a qualifying census tract does not exist, then one 
or more contiguous census blocks that have a population density of at 
least 1,000 ppsm are identified and aggregated. This aggregation of 
continuous census tracts or census blocks, as appropriate, would be 
known as the ``initial urban area core.''
    After the initial urban area core with a population density of 
1,000 ppsm or more is identified, a census tract is included in the 
initial urban area core if it is adjacent to other qualifying territory 
and has a land area less than three square miles and a population 
density of at least 500 ppsm.
    A census block \10\ is included in the initial urban area core if 
it is adjacent to other qualifying territory and
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    \10\ Due to imposed restrictions on the selection of features 
that could be used as census block boundaries within military 
installations for the 2010 Census, blocks on military installations 
that have a population of 2,500 or more are treated as having a 
population density of 1,000 ppsm if the density is less than 1,000 
ppsm. Census blocks that have a population greater than 1,000 and 
less than 2,500 are treated as having a population density of 500 
ppsm.
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    a. Has a population density of at least 500 ppsm; or
    b. At least one-third of the census block consists of territory 
with a level of imperviousness of at least twenty percent,\11\ 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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    \11\ 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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    The Census Bureau would apply proposed criteria 1.a and 1.b above 
until there are no blocks to add to the urban area.
2. 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 topographic or land use conditions.\12\ Such 
``exempted'' territory offsets urban development due to particular land 
use, land cover, or topographic conditions. For the 2010 Census, the 
Census Bureau proposes the following to be exempted territory:
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    \12\ 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 2001 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 \13\).
---------------------------------------------------------------------------

    \13\ For the MRLC's 2001 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.
---------------------------------------------------------------------------

    Noncontiguous qualifying territory would be added to a core when 
separated by exempted territory, provided that:
    a. The road connection across the exempted territory (located on 
both sides of the road) is no greater than five miles; and
    b. The road connection does not cross more than a total of 2.5 
miles of territory not classified as exempted (those segments of the 
road connection where exempted territory is not on both sides of the 
road); and
    c. The total length of the road connection (exempt distance and 
non-exempt distance) is no greater than five miles for a jump and no 
greater than 2.5 miles for a hop.
3. Inclusion of Noncontiguous Territory via Hops and Jumps
    Noncontiguous territory that meets the proposed population density 
criteria specified in section B.1.a and b above, but is separated from 
an initial urban area core of 1,000 or more people, 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 cores that have a 
population of 1,500 or more and add other qualifying territory via a 
jump connection.\14\ Jumps are used to connect densely settled 
noncontiguous territory separated from the core by territory with low 
population density measuring greater than 0.5 and no more than 2.5 road 
miles across. This process recognizes the existence of larger areas of 
non-residential urban uses or other territory with low population 
density that does not provide a substantial barrier to interaction 
between outlying territory with high population density and the main 
body of the urban area. Because it is possible that any given densely 
settled 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.
---------------------------------------------------------------------------

    \14\ All initial urban area cores with a population less than 
1,500 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.
---------------------------------------------------------------------------

    In addition to the distance criteria listed above, a hop or a jump 
will qualify if:
    a. The census tracts and blocks identified in the high density 
destination and along the hop or jump corridor have a combined overall

[[Page 52183]]

population density of at least 500 ppsm, or
    b. The high density destination to be added via the hop or jump has 
a total population of 1,000 or more.
    No additional jumps may originate from a qualifying area after the 
first jump in that direction unless the territory being included as a 
result of the jump was an initial urban area core with a population of 
50,000 or more.
4. Inclusion of Airports
    After all territory has been added to the initial core via hop and 
jump connections, the Census Bureau will then add whole tabulation 
blocks that approximate the territory of major airports, provided at 
least one of the blocks that represent the airport is included within 
or adjacent to the initial core. An airport is identified as a ``major 
airport'' if it had an annual enplanement of at least 2,500 passengers 
in any year between 2000 and the last year of reference in the Federal 
Aviation Administration's (FAA) Air Carrier Activity Information 
System.
5. Inclusion of Enclaves
    The Census Bureau will add enclaves within the urban area, provided 
that they are surrounded only by land, by territory that qualified for 
inclusion in the urban area based on the proposed population 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; or
    b. All area of the enclave is surrounded by territory that 
qualified for inclusion in the initial core, and is more than a 
straight-line distance of 2.5 miles from a land block that is not part 
of the initial core; or
    c. The area of the enclave is less than five square miles, is 
surrounded by both land that qualified for inclusion in the initial 
core and water, and 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 Indentations
    The Census Bureau proposes to evaluate and include territory that 
forms an indentation within the urban area. Including such territory 
will produce a smoother and more manageable boundary for each urban 
area. It would also recognize that small sparsely settled areas that 
are wholly or partially enveloped by urban territory are more likely to 
be affected by and integrated with adjacent urban territory and may 
become more densely settled by future development.
    To determine whether an indentation should be included in the urban 
area, the Census Bureau proposes to identify a ``closure line,'' 
defined as a straight line no more than one mile in length, that 
extends from one point along the edge of the urban area across the 
mouth of the indentation to another point along the edge of the urban 
area.
    A census block located wholly or partially within an indentation 
will be included in the urban area if at least 75 percent of the area 
of the block is inside the closure line. The total area of those blocks 
that meet or exceed the proposed 75 percent criterion is compared to 
the area of a circle, the diameter of which is the length of the 
closure qualification line. The territory within the indentation will 
be included in the urban area if its area is at least four times the 
area of the circle and less than five square miles.
    If the collective area of the census blocks inside the closure line 
does not meet the criteria listed above, the Census Bureau will define 
successive closure lines within the indentation, starting at the mouth 
and working inward toward the base of the indentation, until the 
criteria for inclusion are met or it is determined that the indentation 
will not qualify for inclusion.
7. Splitting Large Agglomerations
    The automated urban area delineation methodology that will be used 
for the 2010 Census may result in large urban agglomerations of 
continuously developed territory. If such results occur, the Census 
Bureau proposes splitting large agglomerations of 1,000,000 or more 
people along metropolitan statistical area boundaries to identify 
individual UAs. In New England, large agglomerations will be split 
based on the boundaries of metropolitan New England city and town areas 
(NECTAs). In situations where an incorporated place or a CDP crosses 
the metropolitan statistical area or metropolitan NECTA boundary, the 
boundary splitting the large agglomeration will be modified to follow 
the incorporated place or CDP boundary. The incorporated place or CDP 
will be assigned to the resulting UA that contains the largest 
proportion of the place's land area. Urban clusters would not be 
created as a result of splitting.
8. 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) 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 a urban area:
    a. The most populous incorporated place with a population of 10,000 
or more within the urban area 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 having at least 2,500 people in the urban 
area.
    Up to two additional places, in descending order of population 
size, may be included in the title of an urban area, provided that:
    a. The place has 250,000 or more people in the urban area; or
    b. The place has at least 2,500 people in the urban area, 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 use the following rules to identify an 
urban area title, applying each in order until a title is identified:
    a. The governmental MCD having the largest total population in the 
urban area; or
    b. A local name recognized for the area by the United States 
Geological Survey (USGS)' Geographic Names Information System (GNIS), 
with preference given to names 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 into which the urban 
area extends. The order of the state names is the same as the order of 
the related place names in the urban area title.
    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 to the larger urban area.
    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

[[Page 52184]]

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.
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 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 
division of a county 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 associated with at least one core (urbanized area or 
urban cluster) 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.
    Exempted Territory: Pre-existing landcover that offsets the pattern 
of urban development.
    Group Quarters (GQs): A place where people live or stay, in a group 
living arrangement,