Census Tracts for the 2020 Census-Proposed Criteria, 6941-6948 [2018-02625]

Agencies

• DEPARTMENT OF COMMERCE
• Bureau of the Census

[Federal Register Volume 83, Number 32 (Thursday, February 15, 2018)]
[Notices]
[Pages 6941-6948]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-02625]


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DEPARTMENT OF COMMERCE

Bureau of the Census

[Docket Number 171005976-7976-01]


Census Tracts for the 2020 Census--Proposed Criteria

AGENCY: Bureau of the Census, Commerce

ACTION: Notice of proposed program and request for comments

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SUMMARY: The Census Bureau is publishing this notice in the Federal 
Register to request comments from the public and other government 
agencies on census tracts. The Census Bureau will respond to the 
comments received as part of the publication of final criteria in the 
Federal Register. After the final criteria are published in the Federal 
Register,the Census Bureau will offer designated governments or 
organizations an opportunity to review and, if necessary, suggest 
updates to the boundaries and attributes of the census tracts in their 
geographic area under the Participant Statistical Areas Program

[[Page 6942]]

(PSAP). In addition to reviewing and updating census tracts, the 
program also reviews and updates census block groups, census designated 
places, census county divisions, and statistical tribal geographic 
areas. The Census Bureau will issue notices in the Federal Register for 
each of these geographies.

DATES: Written comments must be submitted on or before May 16, 2018.

ADDRESSES: Please direct all written comments on this proposed program 
to Vincent Osier, Geographic Standards, Criteria, and Quality Branch, 
Geography Division, U.S. Census Bureau, Room 4H173, 4600 Silver Hill 
Road, Washington, DC 20233-7400. Email: [email protected]. 
Phone: 301-763-9039, or 301-763-3056 (PSAP Hotline).

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, Room 4H173, 4600 Silver Hill Road, Washington, DC 20233-
7400. Email: [email protected]. Phone: 301-763-9039, or 301-763-
3056 (PSAP hotline).

SUPPLEMENTARY INFORMATION: Census tracts are relatively permanent 
small-area geographic divisions of a county or statistically equivalent 
entity \1\ defined for the tabulation and presentation of data from the 
decennial census and selected other statistical programs. Census tracts 
will also be used to tabulate and publish estimates from the American 
Community Survey (ACS) \2\ after 2020 and potentially data from other 
Bureau of the Census (Census Bureau) censuses and surveys.
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    \1\ For the Census Bureau's purposes, the term ``county'' 
includes parishes in Louisiana; boroughs, city and boroughs, 
municipalities, and census areas in Alaska; independent cities in 
Maryland, Missouri, Nevada, and Virginia; districts and islands in 
American Samoa; districts in the U.S. Virgin Islands; municipalities 
in the Commonwealth of the Northern Mariana Islands; municipios in 
Puerto Rico; and the areas constituting the District of Columbia and 
Guam. This notice will refer to all these entities collectively as 
``counties''.
    \2\ The ACS is conducted in the United States and in Puerto 
Rico. In Puerto Rico the survey is called the Puerto Rico Community 
Survey. For ease of discussion, throughout this document the term 
ACS is used to represent the surveys conducted in the United States 
and in Puerto Rico.
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    There are no proposed changes to the existing census tract criteria 
from the 2010 Census; this notice provides only clarifications. The 
history of census tracts and changes implemented for the 2010 Census 
can be found in the Federal Register from March 14, 2008 (73 FR 13836).

I. General Principles and Criteria for Census Tracts for the 2020 
Census

A. General Principles

    1. The primary goal of the census tract is to provide a set of 
nationally consistent small, statistical geographic units, with stable 
boundaries, that facilitate analysis of data across time. A century of 
census tract use has shown that continuity and comparability in tracts 
and their boundaries over time are of considerable importance to data 
users. Pursuant to this goal of maintaining continuity and 
comparability in tracts, the Census Bureau requests that the outer 
boundaries of the tract not be changed when a census tract must be 
updated, for example to meet the minimum or maximum population or 
housing unit thresholds. Instead, Census requests that updates to a 
tract split the tract into two or more tracts, or merge the tract with 
an adjacent tract. The Census Bureau discourages changes to tract 
boundaries (that is, ``retracting''), except in specified 
circumstances, which the Census Bureau will review on a case-by-case 
basis.
    2. In order to ensure a minimal level of reliability in sample data 
and minimize potential disclosures of sensitive information, a census 
tract should contain 1,200 people or 480 housing units at minimum, and 
8,000 people or 3,200 housing units at maximum. A census tract should 
maintain these minimum thresholds unless it is flagged as a special use 
tract (discussed below), or is coextensive with a county with fewer 
than 1,200 people. PSAP participants should aim to create census tracts 
that meet the optimal population of 4,000 or 1,600 housing units. The 
housing unit criterion is used to accommodate areas that are occupied 
seasonally and may otherwise show a discrepancy between decennial and 
ACS population figures.\3\
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    \3\ `Occupied seasonally' refers to seasonal communities in 
which residents often are not present on the date of the decennial 
census, but will be present at other times of the year and for which 
estimates may be reflected in the ACS. The ACS is designed to 
produce local area data based upon a 12-month period estimate (or an 
average).
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    3. The Census Bureau also recognizes that there are significant 
geographic areas that are characterized by unique populations (e.g., 
prisons or universities) or not characterized by residential 
populations at all (e.g., national parks or large bodies of water) 
which local participants may wish to exclude from populated census 
tracts for either analytical or cartographic purposes. These areas may 
be designated as special use census tracts to distinguish them from 
standard populated census tracts. Special use census tracts are not 
required, but if delineated they must be designated as a specific type 
of special use (discussed below), have an official name, ideally have 
no residential population or housing units or at least meet all minimum 
population or housing thresholds mentioned above, and must not create 
noncontiguous census tracts. If located in an urban area, a special use 
census tract must have an area measurement of approximately one square 
mile or more. If delineated completely outside an urban area, a special 
use census tract must have an area of approximately 10 square miles or 
more. The Census Bureau recognizes that some special use areas not 
intended for residential population, such as parks, may contain some 
minimal population, such as caretakers or the homeless; since the 
primary purpose of census tracts is to help provide high-quality 
statistical data about the population, the participant and the Census 
Bureau must decide if a special use census tract would be useful in 
such a situation.
    4. To facilitate the analysis of data for American Indian tribes, 
and to recognize their unique governmental status, program participants 
are encouraged to merge, split, or redefine census tracts to avoid 
unnecessarily splitting American Indian reservations (AIRs) and off-
reservation trust lands (ORTLs). Each contiguous AIR and/or ORTL should 
be included, along with any necessary territory outside the AIR and/or 
ORTL, within a single census tract or as few census tracts as possible 
for the 2020 Census. This is the only situation in which retracting is 
encouraged (Figure 1).

[[Page 6943]]

[GRAPHIC] [TIFF OMITTED] TN15FE18.000

B. Criteria

    The criteria herein apply to the United States, including federally 
recognized AIRs and ORTLs, Puerto Rico, and the Island Areas.\4\ The 
Census Bureau may modify and, if necessary, reject any proposals for 
census tracts that do not meet the published criteria. In addition, the 
Census Bureau reserves the right to modify the boundaries and 
attributes of census tracts as needed to meet the published criteria 
and/or maintain geographic relationships before or after the final 
tabulation geography is set for the 2020 Census.
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    \4\ For Census Bureau purposes, the United States typically 
refers to only the fifty states and the District of Columbia, and 
does not include the U.S. territories (Puerto Rico, the Island 
Areas, and the U.S. Minor Outlying Islands). The Island Areas 
includes American Samoa, the Commonwealth of the Northern Mariana 
Islands, Guam, and the U.S. Virgin 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, Midway 
Islands, Navassa Island, Palmyra Atoll, and Wake Island.
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    The Census Bureau sets forth the following criteria for use in 
reviewing, updating, and delineating 2020 census tracts:
    1. Census tracts must not cross county or state boundaries. This 
criterion takes precedence over all other criteria or requirements 
(except for tribal tracts on federally recognized AIRs and/or ORTLs).
    2. Census tracts must cover the entire land and water area of a 
county.
    3. Census tracts must comprise a reasonably compact and contiguous 
land area.
    Noncontiguous boundaries are permitted only where a contiguous area 
or inaccessible area would not meet population or housing unit count 
requirements for a separate census tract, in which case the 
noncontiguous or inaccessible area must be combined within an adjacent 
or proximate tract. For example, an island that does not meet the 
minimum population threshold for recognition as a separate census tract 
should be combined with other proximate land to form a single, 
contiguous census tract. Each case will be reviewed and accepted at the 
Census Bureau's discretion.
    4. Census tract boundaries should follow visible and identifiable 
features.
    To make the location of census tract boundaries less ambiguous, 
wherever possible, tract boundaries should follow significant, visible, 
easily identifiable features. The use of visible features facilitates 
the location and identification of census tract boundaries in the 
field, both on the ground and in imagery. The selection of permanent 
physical features also increases the stability of the boundaries over 
time, as the locations of many visible features in the landscape tend 
to change infrequently. If census tract boundaries are changed, they 
should not be moved from a more significant feature (e.g., a highway or 
a major river) to a less significant feature (e.g., a neighborhood road 
or a small tributary stream). By definition, state and county 
boundaries must be used as census tract boundaries. The Census

[[Page 6944]]

Bureau also permits the use of incorporated place and minor civil 
division (MCD) boundaries in states where those boundaries tend to 
remain unchanged over time (see Table 1).
    The following features are preferred as census tract boundaries for 
the 2020 Census:
    a. State and county boundaries must always be census tract 
boundaries. This criterion takes precedence over all other boundary 
criteria or requirements.
    b. AIR and ORTL boundaries.
    c. Visible, perennial, stable, relatively permanent natural and 
constructed features, such as roads, shorelines, rivers, perennial 
streams and canals, railroad tracks, or above-ground high-tension power 
lines.
    d. Boundaries of legal and administrative entities in selected 
states. Table 1 identifies by state which MCD and incorporated place 
boundaries may be used as census tract boundaries.
    e. Additionally, the following legally defined administrative 
boundaries would be permitted as census tract boundaries:
    i. Barrio, barrio-pueblo, and subbarrio boundaries in Puerto Rico;
    ii. Census subdistrict and estate boundaries in the U.S. Virgin 
Islands;
    iii. County and island boundaries (both MCD equivalents) in 
American Samoa;
    iv. Election district boundaries in Guam;
    v. Municipal district boundaries in the Commonwealth of the 
Northern Mariana Islands; and
    vi. Alaska Native Regional Corporation boundaries in Alaska, at the 
discretion of the Census Bureau, insofar as such boundaries are 
unambiguous for allocating living quarters as part of 2020 Census 
activities.
    f. The boundaries of large parks, forests, airports, 
penitentiaries/prisons, and/or military installations, provided the 
boundaries are clearly marked or easily recognized in the field in 
imagery and on the ground.
    g. When acceptable visible and governmental boundary features are 
not available for use as census tract boundaries, the Census Bureau 
may, at its discretion, approve other nonstandard visible features, 
such as major ridgelines, above-ground pipelines, intermittent streams, 
or fence lines. The Census Bureau may also accept, on a case-by-case 
basis, relatively short stretches of boundaries of selected nonstandard 
and potentially nonvisible features, such as cadastral and parcel 
boundaries or the straight-line extensions or other lines-of-sight 
between acceptable visible features.

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

[[Page 6945]]

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

    5. Population, Housing Unit, and Area Measurement Thresholds.
    The following are the population, housing unit, and area 
measurement threshold criteria for census tracts (as summarized in 
Table 2). The same population and housing unit thresholds apply to all 
types of non-special use census tracts, including census tracts 
delineated for AIRs and ORTLs, the Island Areas, and encompassing group 
quarters, military installations, and institutions.

                                        Table 2--Census Tract Thresholds
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      Census tract type            Threshold type           Optimum             Minimum             Maximum
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Standard & tribal census       Population threshold.  4,000.............  1,200.............  8,000.
 tracts.                       Housing unit           1,600.............  480...............  3,200.
                                threshold.
Special use census tracts....  Area measurement       none..............  1 square mile.....  none.
                                threshold within an
                                urban area.
Area measurement threshold     none.................  10 square miles...  none..............
 outside an urban area.
                               Population threshold.     None (or very little), or must be within the standard
                                                                        census tract thresholds.
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    a. 2010 Census population counts should be used in census tract 
review in most cases. Housing unit counts should be used for census 
tracts in seasonal communities that have little or no population on 
Census Day (April 1). Locally produced population and housing unit 
estimates can be used when reviewing and updating census tracts, 
especially in areas that have experienced considerable growth since the 
2010 Census.
    b. The housing unit thresholds are based on a national average of 
2.5 persons per household. The Census Bureau recognizes that there are 
local and regional variations to this average, and will take this into 
consideration when reviewing all census tract proposals.
    c. Any census tract with a population or housing unit count less 
than the minimum threshold should be merged with an adjacent census 
tract to form a single tract with at least 1,200 people or at least 480 
housing units (Figure 2). The Census Bureau recognizes the complexity 
that exists between meeting the optimum population or housing unit 
threshold in a census tract and maintaining census tract comparability 
over time. For example, if the population or housing unit count based 
on 2010 Census data was below the minimum thresholds, but significant 
growth has occurred since 2010 or is expected before 2020 for a census 
tract, the census tract should not be merged with another census tract.
    Supporting evidence may be requested by the Census Bureau. However, 
if the census tract's population does not increase as expected and does 
not meet either the minimum population or housing unit thresholds for 
2020, this may adversely affect the reliability and availability of any 
sample estimates for that census tract. For this reason, the Census 
Bureau suggests merging the census tract with another adjacent census 
tract if there is a possibility that anticipated growth will not be 
sufficient to meet minimum thresholds.

[[Page 6946]]

[GRAPHIC] [TIFF OMITTED] TN15FE18.001

    d. For the 2020 Census, the Census Bureau will allow the 
delineation of special use census tracts, but they are not required. A 
special use census tract must be designated as a specific use type 
(e.g., state park), must have an official name (e.g., Jay Cooke State 
Park), must have no (or very little) residential population or meet 
population or housing unit thresholds, and must not create a 
noncontiguous census tract. In some instances, multiple areas can be 
combined to form a single special use census tract if the land 
management characteristics are similar, such as a special use census 
tract comprising adjacent federal and state parks. If the special use 
census tract is delineated in a densely populated, urban area, the 
census tract must have an area of approximately one square mile or 
more. If the special use census tract is delineated completely outside 
an urban area, the census tract must have an area of approximately 10 
square miles or more. Any resulting special use census tract should be 
at least as large in area the adjacent standard, populated census 
tracts.
    6. Identification of Census Tracts.
    a. The Census Bureau assigned each census tract a basic census 
tract identifier composed of no more than four digits and may have a 
two-digit decimal suffix.
    b. The range of acceptable basic census tract identifiers for the 
2020 Census is from 1 to 9989; special use census tracts delineated 
specifically to complete coverage of large water bodies will be 
numbered from 9950 to 9989 in each county; census tracts delineated 
within or to primarily encompass AIRs and/or ORTLs should be numbered 
from 9400 to 9499.
    c. Census tract identifiers must be unique within each county.
    d. Once used, census tract identifiers cannot be reused in a 
subsequent census to reference a completely different area within a 
county. If a census tract is split, each portion may keep the same 
basic 4-digit identifier, but each portion must be given a unique 
suffix. If a census tract that was suffixed for 2010 Census is split, 
each portion must be given a new suffix.
    e. The range of acceptable census tract suffixes is .01 to .98.
    7. Census Tract Types.
    Table 3 provides a summary of the types of census tracts (with 
their respective population, housing unit, and area measurement 
thresholds) that the Census Bureau will use for the 2020 Census.

                                     Table 3--Summary of Census Tract Types
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                                    Distinction from         Population        Housing unit     Area measurement
       Census tract type          standard census tract      thresholds         thresholds         thresholds
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Standard census tract..........  ......................  Optimum: 4,000;    Optimum: 1,600;    None.
                                                          Min: 1,200; Max:   Min: 480; Max:
                                                          8,000.             3,200.
Tribal census tract............  Tribal census tracts    Optimum: 4,000;    Optimum: 1,600;    None.
                                  are conceptually        Min: 1,200; Max:   Min: 480; Max:
                                  similar and             8,000.             3,200.
                                  equivalent to census
                                  tracts defined within
                                  the standard state-
                                  county-tract
                                  geographic hierarchy
                                  used for tabulating
                                  and publishing
                                  statistical data.
Special use census tract.......  A census tract          None (or very      None (or very      Within an urban
                                  encompassing a large    little) or         little) or         area: min. 1
                                  airport, public park,   within the         within the         square mile;
                                  public forest, or       standard census    standard census    Outside an urban
                                  large water body with   tract threshold.   tract threshold.   area: min. 10
                                  no (or very little)                                           square miles.
                                  population or housing
                                  units.
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[[Page 6947]]

C. Tribal Census Tracts

    Tribal census tracts are statistical geographic entities defined by 
the Census Bureau in cooperation with tribal officials to provide 
meaningful, relevant, and reliable data for small geographic areas 
within the boundaries of federally recognized AIRs and/or ORTLs. As 
such, they recognize the unique statistical data needs of federally 
recognized American Indian tribes. The delineation of tribal census 
tracts allows for an unambiguous presentation of census tract-level 
data specific to the federally recognized AIR and/or ORTL without the 
imposition of state or county boundaries, which might artificially 
separate American Indian populations located within a single AIR and/or 
ORTL. To this end, the American Indian tribal participant may define 
tribal census tracts that cross county or state boundaries, or both. 
For federally recognized American Indian tribes with AIRs and/or ORTLs 
that have more than 2,400 residents, the Census Bureau will offer the 
tribal government the opportunity to delineate tribal census tracts and 
other tribal statistical geography on their AIR and/or ORTL. For 
federally recognized tribes with an AIR and/or ORTL that has fewer than 
2,400 residents, the Census Bureau will define one tribal census tract 
coextensive with the AIR and/or ORTL. Tribal census tracts must be 
delineated to meet all other census tract criteria, and must be 
identified uniquely so as to clearly distinguish them from county-based 
census tracts. Tribal census tracts are conceptually similar and 
equivalent to census tracts defined within the standard state-county-
tract geographic hierarchy used for tabulating and publishing 
statistical data.
    In order to provide meaningful statistical geographic areas within 
the AIR and/or ORTL, as well as make meaningful and reliable data 
available for these areas and their populations, tribal census tract 
geography is maintained separately from standard county-based census 
tracts. This change was first introduced for the 2010 Census, creating 
standard, county-based census tracts nationwide and maintaining tribal 
census tracts as a completely separate set of geography from standard 
census tracts for both geographic and data presentation purposes, and 
eliminating, in part, the reliability and availability data issues for 
the tribal census tracts and the derived standard census tracts that 
were present in Census 2000.\5\
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    \5\ For Census 2000, tribal tracts were defined for federally 
recognized AIRs and/or ORTLs and standard census tracts were 
identified by superimposing county and state boundaries onto the 
tribal tracts. For Census 2000 products in which data were presented 
by state and county, the standard state-county-census tract 
hierarchy was maintained, even for territory contained within an AIR 
and/or ORTL. In such instances, the state-county portions of a 
tribal tract were identified as individual census tracts. These 
standard census tracts may not have met the minimum population 
thresholds, potentially limiting sample data reliability or 
availability for both the tribal tract and the derived standard 
census tracts.
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    As with standard census tracts submitted through this program, the 
tribal census tracts are submitted to the Census Bureau, and are 
subject to review to ensure compliance with the published criteria. 
Detailed criteria pertaining to tribal census tracts will be published 
in a separate Federal Register notice pertaining to all American Indian 
areas, including statistical areas defined through the PSAP.

II. Definitions of Key Terms

    Alaska Native Regional Corporation (ANRC)--A corporate geographic 
area established under the Alaska Native Claims Settlement Act (Pub. L. 
92-203, 85 Stat. 688 (1971)) to conduct both the business and nonprofit 
affairs of Alaska Natives. Twelve ANRCs cover the entire state of 
Alaska except for the Annette Island Reserve.
    American Indian off-reservation trust land (ORTL)--An area of land 
located outside the boundaries of an AIR, whose boundaries are 
established by deed, and which are held in trust by the U.S. Federal 
government for a federally recognized American Indian tribe or members 
of that tribe.
    American Indian reservation (AIR)--An area of land with boundaries 
established by final treaty, statute, executive order, and/or court 
order and over which a federally recognized American Indian tribal 
government has governmental authority. Along with reservation, 
designations such as colonies, communities, pueblos, rancherias, and 
reserves apply to AIRs.
    Block group--A statistical subdivision of a census tract consisting 
of all census blocks whose numbers begin with the same digit in a 
census tract. A block group is the smallest geographic entity for which 
the Census Bureau normally tabulates sample data.
    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 and 
publishes decennial census data.
    Census county division (CCD)--Areas delineated by the Census Bureau 
in cooperation with state, tribal, and local officials for statistical 
purposes. CCDs have no legal function and are not governmental units. 
CCD boundaries usually follow visible features and usually coincide 
with census tract boundaries. The name of each CCD is based on a place, 
county, or well-known local name that identifies its location.
    Census designated place (CDP)--A statistical geographic entity 
equivalent to an incorporated place with a concentration of population, 
housing, and commercial and nonresidential structures that is 
identifiable by name, but is not within an incorporated place.
    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 census tracts is to provide a 
set of nationally consistent, relatively small, statistical geographic 
units, with stable boundaries that facilitate analysis of data across 
time and between decennial censuses.
    Conjoint--A description of a boundary line shared by two adjacent 
geographic entities.
    Contiguous--A description of areas sharing common boundary lines, 
more than a single point, such that the areas, when combined, form a 
single piece of territory. Noncontiguous areas form disjoint pieces.
    Group quarters--A location where people live or stay, in a group 
living arrangement, that is owned or managed by an entity or 
organization providing housing and/or services for the residents. This 
is not a typical household-type living arrangement. These services may 
include custodial or medical care as well as other types of assistance, 
and residency is commonly restricted to those receiving these services. 
People living in group quarters are usually not related to each other. 
Group quarters include such places as college residence halls, 
residential treatment centers, skilled nursing facilities, group homes, 
military barracks, correctional facilities, and workers' dormitories.
    Incorporated place--A type of governmental unit, incorporated under 
state law as a city, town (except in New England, New York, and 
Wisconsin), borough (except in Alaska and New York), or village, 
generally to provide governmental services for a concentration of 
people within legally prescribed boundaries.
    Minor civil division (MCD)--The primary governmental or 
administrative division of a county in 28 states and the Island Areas 
having legal boundaries, names, and descriptions. The MCDs represent 
many different types of legal entities with a wide variety of 
characteristics, powers, and functions

[[Page 6948]]

depending on the state and type of MCD. In some states, some or all of 
the incorporated places also constitute MCDs.
    Nonvisible feature--A map feature that is not visible on the 
ground, such as a city or county boundary through space, a property 
line, or line-of-sight extension of a road.
    Retracting--Substantially changing the boundaries of a census tract 
so that comparability over time is not maintained.
    Special use census tract--Type of census tract that must be 
designated as a specific use type (e.g., state park or large lake) and 
have an official name (e.g., Jay Cooke State Park or Lake Minnetonka), 
must have little or no population or housing units, and must not create 
a noncontiguous census tract. If delineated in a densely populated, 
urban area, a special use census tract must have an area of at least 
one square mile. If delineated completely outside an urban area, a 
special use census tract must have an area of at least 10 square miles.
    Visible feature--A map feature that can be seen on the ground and 
in imagery, such as a road, railroad track, major above-ground 
transmission line or pipeline, river, stream, shoreline, fence, sharply 
defined mountain ridge, or cliff. A nonstandard visible feature is a 
feature that may not be clearly defined on the ground (such as a 
ridge), may be seasonal (such as an intermittent stream), or may be 
relatively impermanent (such as a fence). The Census Bureau generally 
requests verification that nonstandard features used as boundaries for 
the PSAP geographic areas pose no problem in their location during 
field work.

    Dated: January 31, 2018.
Ron S. Jarmin,
Associate Director for Economic Programs, Performing the Non-Exclusive 
Functions and Duties of the Director, Bureau of the Census.
[FR Doc. 2018-02625 Filed 2-14-18; 8:45 am]
BILLING CODE 3510-07-P