Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 17337 

1The ACS is conducted in the United States and 

in Puerto Rico. In Puerto Rico, the survey is called 

the Puerto Rico Community Survey. For ease of 

discussion, throughout this document the term ACS 

is used to represent both the survey that is 

conducted in the United States and in Puerto Rico. 

2For Census Bureau purposes, the United States 

includes the fifty states and the District of 

Columbia. 

3The proposed criteria for the tribal statistical 

areas program will be outlined in a separate Federal 

Register notice. In the tribal statistical areas 

program, federally recognized American Indian 

tribes that have a reservation and/or off-reservation 

trust land may delineate census designated places 

and, if these areas have a population of 2,400 or 

greater, may delineate tribal tracts and tribal block 

groups for their reservation and off-reservation trust 

land. 

4For Census Bureau purposes, the Island Areas 

includes American Samoa, the Commonwealth of 

the Northern Mariana Islands, Guam, the U.S. 

Virgin Islands, and the U.S. Minor Outlying Islands. 

The U.S. Minor Outlying Islands is an aggregation 

of nine U.S. territories: Baker Island, Howland 

Island, Jarvis Island, Johnston Atoll, Kingman Reef, 

Midway Islands, Navassa Island, Palmyra Atoll, and 

Wake Island. 

numerous geographic areas for which 

the Census Bureau tabulates data from 

its censuses and surveys. 

Visible feature—A map feature that 

can be seen on the ground such as a 

road, railroad track, major above-ground 

transmission line or pipeline, river, 

stream, shoreline, fence, sharply defined 

mountain ridge, or cliff. A nonstandard 

visible feature is a feature that may not 

be clearly defined on the ground (such 

as a ridge), may be seasonal (such as an 

intermittent stream), or may be 

relatively impermanent (such as a 

fence). The Census Bureau generally 

requests verification that nonstandard 

features used as boundaries for the 

PSAP geographic areas pose no problem 

in their location during field work. 

Water body tract—Type of tract 

encompassing territorial seas, coastal 

water, the Great Lakes, or inland water 

at least 100 square miles in area. If an 

inland water body meets this criterion, 

each county can delineate a tract for its 

portion of the water body. 

Executive Order 12866 

This notice has been determined to be 

not significant under Executive Order 

12866. 

Paperwork Reduction Act 

This program notice does not 

represent a collection of information 

subject to the requirements of the 

Paperwork Reduction Act, 44 U.S.C. 

Chapter 35. 

Dated: April 3, 2007. 

Charles Louis Kincannon, 

Director, Bureau of the Census. 

[FR Doc. E7–6466 Filed 4–5–07; 8:45 am] 

BILLING CODE 3510–07–P 

DEPARTMENT OF COMMERCE 

Bureau of the Census 

[Docket Number 070126022–0723–01] 

Census Block Group Program for the 

2010 Census—Proposed Criteria 

AGENCY: Bureau of the Census, 

Commerce. 

ACTION: Notice of proposed program 

revisions and request for comments. 

SUMMARY: Block groups are statistical 

geographic divisions of a census tract, 

defined for the tabulation and 

dissemination of decennial census data. 

Block groups also will be used to 

tabulate and publish estimates from the 

American Community Survey (ACS) 1

after 2010. Each block group comprises 

a reasonably compact and contiguous 

cluster of census blocks; up to nine 

block groups can be contained within a 

single census tract. 

Most provisions of the block group 

criteria for the 2010 Census remain 

unchanged from those used in 

conjunction with Census 2000. 

However, based on consultation with 

data users and internal review, the 

Bureau of the Census (Census Bureau) is 

proposing the following changes for the 

2010 Census: (1) Increasing the 

minimum population and housing unit 

counts for block groups; (2) using 

housing unit counts (as an alternative to 

population counts) in the delineation of 

block groups; (3) applying the same 

population and housing unit thresholds 

to all types of populated block groups in 

the United States,2 including block 

groups delineated on American Indian 

reservations and/or off-reservation trust 

lands,3 the Island Areas,4 and 

encompassing group quarters, military 

installations, and institutions; (4) 

allowing the delineation of block groups 

for large water bodies with areas of 

approximately 100 square miles or more 

and special land uses (e.g., large airports 

or public parks) with an official name; 

and (5) allowing for geographic 

frameworks of tribal block groups 

(separate from the standard block 

groups defined within counties and 

standard census tracts) to be defined 

within federally-recognized American 

Indian reservations and/or offreservation trust lands. 

In addition to the proposed criteria, 

this notice includes a description of the 

changes from the criteria used for 

Census 2000 and a list of definitions of 

key terms used in the criteria. 

The Census Bureau is publishing this 

notice in the Federal Register to request 

comments from the public and other 

government agencies. The Census 

Bureau will respond to the comments 

received as part of the publication of 

final criteria in the Federal Register. 

After the final criteria are published in 

the Federal Register, the Census Bureau 

will offer designated governments or 

organizations an opportunity to review 

and, if necessary, suggest updates to the 

boundaries and attributes of the block 

groups in their geographic area under 

the Participant Statistical Areas Program 

(PSAP). In addition to block groups, the 

program also encompasses the review 

and update of census tracts, census 

designated places, and census county 

divisions. 

DATES: Written comments must be 

submitted on or before July 5, 2007. 

ADDRESSES: Please direct all written 

comments on this proposed program to 

the Director, U.S. Census Bureau, Room 

8H001, Mail Stop 0100, Washington, DC 

20233–0001. 

FOR FURTHER INFORMATION CONTACT: 

Requests for additional information on 

this proposed program should be 

directed to Michael Ratcliffe, Chief, 

Geographic Standards and Criteria 

Branch, Geography Division, U.S. 

Census Bureau, via e-mail at 

geo.psap.list@census.gov or telephone at 

301–763–3056. 

SUPPLEMENTARY INFORMATION: 

I. History of Block Groups 

The Census Bureau first delineated 

block groups as statistical geographic 

divisions of census tracts for the 1970 

Census, comprising contiguous 

combinations of census blocks for data 

presentation purposes. At that time, 

census block groups only existed in 

urbanized areas in which census blocks 

were defined. Block groups were 

defined without regard to political and 

administrative boundaries, with an 

average population of 1,000, and to be 

approximately equal in area. 

As census block, block group, and 

census tract data were used increasingly 

by data users, the Census Bureau 

expanded these programs to cover 

additional geographic areas, while 

redefining the population threshold 

criteria to more adequately suit data 

users’ needs. The 1990 Census was the 

first in which census blocks and block 

groups were defined throughout the 

entirety of the United States, Puerto 

Rico, and the Island Areas. For Census 

2000, as with census tracts, the Census 

Bureau increased the number of 

geographic areas whose boundaries 

could be used as block group 

boundaries, and allowed tribal 

governments of federally recognized 


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American Indian tribes with a 

reservation and/or off-reservation trust 

lands to delineate block groups without 

regard to state and/or county 

boundaries, provided the tribe had a 

1990 Census population of at least 

1,000. 

II. General Principles and Criteria for 

Block Groups for the 2010 Census 

A. General Principles 

1. Block groups are statistical 

geographic divisions of a census tract, 

defined by the Census Bureau in 

cooperation with local officials and 

organizations, for the tabulation and 

dissemination of decennial census data 

as well as period estimates of 

demographic and housing 

characteristics from the ACS. 

2. Because block groups are used to 

present and analyze sample-based 

statistical data, the amount of 

population or housing units within a 

block group is an important 

consideration. As a general rule, 

estimates from programs providing 

sample data, including the ACS, for 

geographic areas with smaller 

populations are subject to higher 

variances than comparable estimates for 

areas with larger populations. Aiming to 

create block groups that fall between the 

minimum and maximum thresholds 

will improve the reliability and 

availability of data, and local 

governments and planners should 

consider these factors when defining 

their block groups. 

3. Block groups form the geographic 

framework within which the Census 

Bureau defines census blocks for use in 

tabulating and presenting decennial 

census data. Census blocks are 

numbered within block groups. 

4. Geographic areas that are not 

characterized by a residential 

population, such as parks, large 

industrial areas, and water bodies, and 

which local participants may wish to 

separate from populated census tracts 

for analytical or cartographic purposes, 

or both, may be identified as individual 

block groups. 

B. Proposed Changes to the Block Group 

Criteria for the 2010 Census 

Most provisions of the block group 

criteria for the 2010 Census would 

remain unchanged from those used in 

conjunction with Census 2000 with the 

following exceptions: 

1. The Census Bureau proposes to 

increase the minimum population and 

housing unit counts for block groups to 

1,200 and 480, respectively, to support 

block group sample data reliability and 

availability and to lower the variance of 

the sample data. The sample size for the 

ACS is smaller than the sample from the 

decennial census long form of previous 

censuses. As a general rule, estimates 

from programs providing sample data, 

including the ACS, for geographic areas 

with smaller populations will be subject 

to higher variances than comparable 

estimates for areas with larger 

populations. In addition, the Census 

Bureau’s disclosure rules will have the 

effect of restricting the availability and 

amount of data for areas with small 

populations. Aiming to create block 

groups that fall between the minimum 

and maximum thresholds will improve 

the reliability and availability of data, 

and local governments and planners 

should consider these factors when 

defining their block groups. 

2. Housing unit counts may be used 

instead of population counts in the 

delineation of block groups. This change 

seeks to accommodate seasonal 

communities in which residents may 

not be present on the date of the 

decennial census, but will be present at 

other times of the year and for which 

data may be reflected in the ACS. 

3. For Census 2000, minimum 

population thresholds for block groups 

varied. The minimum population 

threshold for block groups delineated on 

American Indian reservations and offreservation trust lands was 300. This 

differed from the minimum threshold of 

600 people for block groups defined 

elsewhere in the United States, as well 

as in Puerto Rico and the Island Areas. 

The maximum population for a block 

group in any of these areas was 3,000. 

In addition, for Census 2000, block 

groups that enclosed an institution, a 

military installation, or other ‘‘special 

place’’ had a minimum population 

requirement of 300 inhabitants, with no 

optimum or maximum population. 

For the 2010 Census, the same 

population and housing unit thresholds 

(minimum: 1,200 inhabitants or 480 

housing units; maximum: 3,000 

inhabitants or 1,200 housing units) 

would apply to all types of populated 

block groups, including block groups 

delineated for American Indian 

reservations and off-reservation trust 

lands, the Island Areas, and 

encompassing group quarters, military 

installations, and institutions. The 

Census Bureau proposes this change in 

order to aid in the availability and 

reliability of data for all block groups 

and to create a single national standard. 

4. The delineation of block groups 

would be permitted, and encouraged, 

for the following specific types of 

geographic areas: 

a. Large water bodies with areas of 

approximately 100 square miles or 

more. 

b. Special land uses (e.g., large 

airports, public parks, or public forests) 

with an official name. 

A single water body or special land 

use block group will be delineated to be 

coextensive with, or covering the same 

territory as, the water body or special 

land use tract in which it is located. 

The Census Bureau would require 

that block groups delineated to 

encompass large water bodies and 

special land uses have little or no 

residential population. The Census 

Bureau recognizes that some special 

land use areas not generally intended 

for residential population, such as 

parks, may contain some population, 

such as caretakers or the homeless. Our 

intent is to allow for the delineation of 

parks and other special land use areas 

as separate block groups and, therefore, 

will accept such areas as block groups 

even if some residential population is 

present. All such block groups would 

meet all other block group criteria. 

5. A geographic framework of tribal 

block groups, separate from the standard 

block groups defined within counties, 

may be defined within federally 

recognized American Indian 

reservations and/or off-reservation trust 

lands, subject to other population, 

housing, and boundary criteria 

contained in this document. This 

represents a change from the practice for 

Census 2000. The Census Bureau 

proposes this change to better recognize 

the unique statistical data needs of 

federally recognized American Indian 

tribes and their reservation and offreservation trust lands. 

C. Block Group Criteria for the 2010 

Census 

The criteria proposed herein apply to 

the United States, including federally 

recognized American Indian 

reservations and off-reservation trust 

lands, Puerto Rico, and the Island Areas. 

In accordance with the final criteria, the 

Census Bureau may modify and, if 

necessary, reject any proposals for block 

groups that do not meet the established 

criteria. In addition, the Census Bureau 

reserves the right to modify the 

boundaries and attributes of block 

groups as needed to meet the published 

criteria and/or maintain geographic 

relationships before the final tabulation 

geography is set for the 2010 Census. 

The Census Bureau proposes the 

following criteria for use in delineating 

2010 Census block groups. 

1. A block group must comprise a 

reasonable compact, contiguous land 

area. 


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Noncontiguous boundaries are 

permitted only where a contiguous area 

or inaccessible area would not meet 

population or housing unit count 

requirements for a separate block group, 

in which case the noncontiguous or 

inaccessible area must be combined 

within an adjacent or proximate block 

group. For example, an island that does 

not meet the minimum population 

threshold for recognition as a separate 

block group should be combined with 

other proximate land to form a single 

block group. Each case will be reviewed 

and accepted at the Census Bureau’s 

discretion. 

2. Block groups must not cross census 

tract boundaries. 

This criterion supersedes all 

population and housing unit 

requirements or guidelines. By 

extension, because census tracts cannot 

cross county and state boundaries, 

neither can block groups. It is only 

permissible to define a standard block 

group with less than 1,200 people in a 

county that has a population less than 

1,200. 

3. Block groups must cover the entire 

land and water area of each census tract. 

Because census tracts must cover the 

entire area of a county, by definition 

block groups also must cover the entire 

area of each county. In counties 

containing coastal waters, territorial sea, 

and portions of the Great Lakes, and 

very large, contiguous, inland water 

bodies, a single water body tract and a 

coextensive block group should be 

created for each discrete water body to 

provide for complete census block 

group coverage. 

4. Block group boundaries should 

follow visible and identifiable features. 

To make the location of block group 

boundaries less ambiguous, wherever 

possible, block group boundaries should 

follow visible and identifiable features. 

The Census Bureau also permits the use 

of state and county boundaries in all 

states and incorporated place and minor 

civil division boundaries in states where 

those boundaries tend to remain 

unchanged over time (see Table 1). The 

use of visible features also makes it 

easier to locate and identify block group 

boundaries over time as the locations of 

many visible features in the landscape 

tend to change infrequently. 

The following features are preferred 

as block group boundaries for the 2010 

Census: 

a. State, county, and census tract 

boundaries must always be block group 

boundaries. This criterion takes 

precedence over all other criteria or 

requirements. 

b. American Indian reservation and 

off-reservation trust land boundaries. 

c. Visible, perennial natural and 

cultural features, such as roads, 

shorelines, rivers, perennial streams and 

canals, railroad tracks, or above-ground 

high-tension power lines. 

d. Boundaries of legal and 

administrative entities in selected states. 

Table 1 identifies by state which minor 

civil division (MCD) and incorporated 

place boundaries may be used as block 

group boundaries. 

TABLE 1.—ACCEPTABLE MCD AND INCORPORATED PLACE BOUNDARIES

Boundaries All MCD 

boundaries 

Boundaries 

of MCDs 

not coincident with 

the boundaries of incorporated 

places that 

themselves 

are MCDs 

All incorporated 

place 

boundaries 

Only conjoint incorporated 

place 

boundaries 

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 ............................................................................................................................... .................... Xa .................... X 

Indiana ............................................................................................................................. X .................... .................... X 

Iowa ................................................................................................................................. .................... X .................... X 

Kansas ............................................................................................................................. .................... X .................... X 

Kentucky .......................................................................................................................... .................... .................... .................... X 

Louisiana .......................................................................................................................... .................... .................... .................... X 

Maine ............................................................................................................................... X .................... X ....................

Maryland .......................................................................................................................... .................... .................... .................... X 

Massachusetts ................................................................................................................. X .................... X ....................

Michigan ........................................................................................................................... .................... X .................... X 

Minnesota ........................................................................................................................ .................... X .................... X 

Mississippi ........................................................................................................................ .................... .................... .................... X 

Missouri ............................................................................................................................ .................... Xb .................... X 

Montana ........................................................................................................................... .................... .................... .................... X 

Nebraska .......................................................................................................................... .................... Xa .................... X 

Nevada ............................................................................................................................. .................... .................... .................... X 

New Hampshire ............................................................................................................... X .................... X ....................

New Jersey ...................................................................................................................... X .................... X ....................

New Mexico ..................................................................................................................... .................... .................... .................... X 

New York ......................................................................................................................... X .................... X ....................

North Carolina .................................................................................................................. .................... .................... .................... X 


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TABLE 1.—ACCEPTABLE MCD AND INCORPORATED PLACE BOUNDARIES—Continued 

Boundaries All MCD 

boundaries 

Boundaries 

of MCDs 

not coincident with 

the boundaries of incorporated 

places that 

themselves 

are MCDs 

All incorporated 

place 

boundaries 

Only conjoint incorporated 

place 

boundaries 

North Dakota .................................................................................................................... .................... X .................... X 

Ohio ................................................................................................................................. .................... X .................... X 

Oklahoma ......................................................................................................................... .................... .................... .................... X 

Oregon ............................................................................................................................. .................... .................... .................... X 

Pennsylvania .................................................................................................................... X .................... X ....................

Rhode Island .................................................................................................................... X .................... X ....................

South Carolina ................................................................................................................. .................... .................... .................... X 

South Dakota ................................................................................................................... .................... X .................... X 

Tennessee ....................................................................................................................... .................... .................... .................... X 

Texas ............................................................................................................................... .................... .................... .................... X 

Utah ................................................................................................................................. .................... .................... .................... X 

Vermont ........................................................................................................................... X .................... X ....................

Virginia ............................................................................................................................. .................... .................... .................... X 

Washington ...................................................................................................................... .................... .................... .................... X 

West Virginia .................................................................................................................... .................... .................... .................... X 

Wisconsin ......................................................................................................................... .................... X .................... X 

Wyoming .......................................................................................................................... .................... .................... .................... X 

aTownships only. 

bGovernmental townships only. 

e. Additionally, the following legally 

defined, administrative boundaries 

would be permitted as block group 

boundaries: 

i. Barrio, barrio-pueblo, and subbarrio 

boundaries in Puerto Rico; 

ii. Census subdistrict boundaries in 

the U.S. Virgin Islands; 

iii. County and island boundaries 

(both MCD equivalents) in American 

Samoa; 

iv. Election district boundaries in 

Guam; 

v. Municipal district boundaries in 

the Commonwealth of the Northern 

Mariana Islands; and 

vi. Alaska Native regional corporation 

boundaries in Alaska, at the discretion 

of the Census Bureau, insofar as such 

boundaries are unambiguous for 

allocating living quarters as part of 2010 

Census activities. 

f. When acceptable visible and 

governmental boundary features are not 

available for use as block group 

boundaries, the Census Bureau may, at 

its discretion, approve other 

nonstandard visible features, such as 

ridge lines, above-ground pipelines, 

intermittent streams, or fence lines. The 

Census Bureau may also accept, on a 

case-by-case basis, the boundaries of 

selected nonstandard and potentially 

nonvisible features, such as the 

boundaries of military installations, 

National Parks, National Monuments, 

National Forests, other types of parks or 

forests, airports, marine ports, 

cemeteries, golf courses, penitentiaries/ 

prisons, glaciers, or the straight-line 

extensions of visible features and other 

lines-of-sight. 

g. The boundaries of large water 

bodies and special land use tracts, 

including parks, forests, and military 

installations, provided the boundaries 

are clearly marked or easily recognized. 

5. Population, Housing Unit, and Area 

Thresholds 

The Census Bureau proposes the 

following population, housing unit, and 

area threshold criteria for census block 

group (as suggested in Table 2). Any 

block group that does not meet the 

minimum population or housing unit 

threshold must be revised. 

TABLE 2.—BLOCK GROUP THRESHOLDS

Block group type Threshold type Minimum Maximum 

Standard & tribal block groups ..................................... Population threshold ..................................................... 1,200 3,000 

Housing Unit threshold ................................................. 480 1,200. 

Water body block groups ............................................. Area threshold (square miles) ...................................... 100 none 

Special land use block groups ..................................... Area threshold for an urban area (square miles) ......... 1 none 

Area threshold outside an urban area (square miles) 10 none 

a. Census 2000 population counts 

should be used in census block group 

review in most cases. Housing unit 

counts should be used for block groups 

in seasonal communities that have no or 

low population on census day (April 1). 

Locally produced population and 

housing unit estimates can be used 

when reviewing and updating block 

groups, especially in areas that have 

experienced considerable growth since 

Census 2000. 

b. The housing unit thresholds are 

based on a national average of 2.5 

persons per household. The Census 

Bureau recognizes that there are 

regional variations to this average, and 

will take this into consideration when 

reviewing all census block group 

proposals. 


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5For federally recognized American Indian tribes 

with reservations and/or off-reservation trust lands 

that have more than 2,400 residents, the Census 

Bureau will offer the tribal government the 

opportunity to delineate tribal block groups and 

other tribal statistical geography on their 

reservation and/or off-reservation trust land. For 

federally recognized tribes with an American Indian 

reservation and/or off-reservation trust land that 

have fewer than 2,400 residents, the Census Bureau 

will define one tribal tract and one tribal block 

group coextensive with the American Indian 

reservation and/or off-reservation trust land. 

c. For the 2010 Census, the Census 

Bureau encourages the delineation of 

special use census tracts, hence special 

use block groups, in specific types of 

areas: 

i. A special land use block group must 

be designated as a specific land use type 

(e.g. state park), must have an official 

name (e.g., Jay Cooke State Park), have 

little or no residential population, and 

must not create a noncontiguous block 

group. In some instances, multiple areas 

can be combined to form a single special 

land use block group if the land 

management characteristics are similar, 

such as a special land use block group 

comprising adjacent federal and state 

parks. If the special land use block 

group is delineated in a densely 

populated, urban area, the block group 

must have an area of approximately one 

square mile or more. If the special land 

use block group is delineated 

completely outside an urban area, the 

block group must have an area of 

approximately 10 square miles or more. 

ii. A water body block group must 

encompass all or part of a territorial sea, 

coastal water, a Great Lake, or an inland 

water body at least 100 square miles in 

area. If an inland water body meets this 

criterion and is in more than one 

county, each county can delineate a 

block group for its portion of the water 

body. Any islands within a qualifying 

water body should be included within 

a separate block group. 

6. Identification of Block Groups 

a. A block group encompasses a 

cluster of census blocks. Each block 

group is identified using a single-digit 

number that will correspond to the first 

digit in the number of each block that 

comprises it. For example, census block 

group 3 includes all census blocks 

numbered in the 3000 range within a 

single census tract. 

b. The range of acceptable block group 

numbers is 1 through 9. Block group 

numbers must always be unique within 

a census tract. 

7. Block Group Types 

TABLE 3.—TABLE 3 BELOW CONTAINS A SUMMARY OF THE TYPES OF BLOCK GROUPS (WITH THEIR RESPECTIVE POPULATION, HOUSING UNIT AND AREA CHARACTERISTICS) THAT THE CENSUS BUREAU PROPOSES TO USE FOR THE 2010 

CENSUS. SUMMARY OF BLOCK GROUP TYPES

How distinct from standard block groups Population thresholds Housing unit thresholds Area thresholds 

Standard & tribal 

block groups.

Tribal block groups are conceptually similar 

and equivalent to census block groups defined within the standard state-countytract-block group geographic hierarchy 

used for tabulating and publishing statistical data.

Minimum: 1,200; Maximum: 3,000.Minimum: 480; Maximum: 1,200.none. 

Water body block 

groups.

A block group coextensive with a water body 

tract, encompassing all or part of a territorial sea, coastal water, a Great Lake, or 

an inland water body at least 100 square 

miles area.

Zero ............................ Zero ............................ 100 square miles if an 

inland water body. 

Special land use block 

groups.

A block group coextensive with a special 

land use tract, encompassing a large airport, public park, or public forest with little 

or no population or housing units. In a 

densely populated, urban area, a special 

land use block group must be approximately one square mile in area or greater. 

If delineated completely outside an urban 

area, a special land use block group must 

have an area of ten square miles or greater.

Little or none .............. Little or none .............. one square mile within 

an urban area/ten 

square miles outside an urban area. 

D. Tribal Block Groups 

Tribal block groups are statistical 

geographic entities defined by the 

Census Bureau in cooperation with 

tribal officials to provide meaningful, 

relevant, and reliable data for small 

geographic areas within the boundaries 

of federally recognized American Indian 

reservations and/or off-reservation trust 

lands. As such, they recognize the 

unique statistical data needs of federally 

recognized American Indian tribes. The 

delineation of tribal block groups allows 

for an unambiguous presentation of 

statistical data specific to a federally 

recognized reservation and/or offreservation trust lands without the 

imposition of state or county 

boundaries, which might artificially 

separate American Indian populations 

located within a single reservation and/ 

or off-reservation trust land. To this end, 

the American Indian tribal participant 5

may define tribal block groups that cross 

county or state boundaries, or both. 

Tribal block groups must be delineated 

to meet all other census block group 

criteria, and must be numbered 

uniquely so as to clearly distinguish 

them from county-based block groups. 

Tribal block group boundaries will be 

held as census block boundaries. Census 

blocks, however, will be numbered 

uniquely within county-based block 

groups. Tribal block groups are 

conceptually similar and equivalent to 

census block groups defined within the 

standard state-county-tract-block group 

geographic hierarchy used for tabulating 

and publishing statistical data. 

In order to provide meaningful 

statistical geographic areas within the 

reservation and/or off-reservation trust 

land, as well as make meaningful and 

reliable data available for these areas 

and their populations, the Census 

Bureau proposes that for the 2010 

Census, standard block groups be 

delineated nationwide, and the tribal 


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17342 Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 

block group geography be maintained 

separately, and defined through a 

separate program designed specifically 

for tribal statistical geography. This 

differs from the procedure for Census 

2000 in which tribal block groups were 

defined for federally recognized 

American Indian reservations and/or 

off-reservation trust lands, and standard 

block groups were identified by 

superimposing county and state 

boundaries onto the tribal block groups. 

For Census 2000 products in which 

data were presented by state and 

county, the standard state-countycensus tract-block group hierarchy was 

maintained, even for territory contained 

within an American Indian reservation 

and/or off-reservation trust land. In such 

instances, the state/county portions of 

tribal block groups were identified as 

individual block groups, and these 

standard block groups may not have met 

the minimum population or housing 

unit thresholds, potentially limiting 

sample data reliability or availability for 

both the tribal block group and the 

derived standard block groups. The 

proposed change in the tribal block 

group program for the 2010 Census, 

creating standard block groups 

nationwide and maintaining tribal block 

groups as a completely separate set of 

geography from standard block groups 

in both geographic and data 

presentation purposes, seeks to 

eliminate, in part, these data issues from 

Census 2000. 

As with standard block groups 

submitted through the program, the 

tribal block groups would be submitted 

to the Census Bureau, and would be 

subject to review to ensure compliance 

with the final published criteria. Tribal 

block groups will be defined as part of 

a separate Tribal Statistical Areas 

Program (TSAP) for the 2010 Census. 

Detailed criteria pertaining to tribal 

block groups will be published in a 

separate Federal Register notice 

pertaining to all American Indian 

statistical areas defined through the 

TSAP. 

III. Definitions of Key Terms 

Alaska Native regional corporation 

(ANRC)—A corporate geographic area 

established under the Alaska Native 

Claims Settlement Act (Pub. L. 92–203), 

to conduct both, the business and 

nonprofit affairs of Alaska Natives. 

Twelve ANRCs cover the entire State of 

Alaska except for the Annette Island 

Reserve. 

American Indian off-reservation trust 

land (ORTL)—A federally recognized 

American Indian land area located 

outside the boundaries of an American 

Indian reservation whose boundaries are 

established by deed and over which a 

federally recognized American Indian 

tribal government has governmental 

authority. 

American Indian reservation (AIR)—A 

federally recognized American Indian 

land area with boundaries established 

by final treaty, statute, executive order, 

and/or court order and over which a 

federally recognized American Indian 

tribal government has governmental 

authority. Along with reservation, 

designations such as colonies, 

communities, pueblos, rancherias, and 

reserves apply to AIRs. 

Coastal water—Water bodies between 

territorial seas and inland water, the 

encompassing headlands being more 

than one mile apart and less than 24 

miles apart. 

Conjoint—A description of a 

boundary shared by two adjacent 

geographic entities. 

Contiguous—A description of areas 

sharing common boundaries, such that 

the areas, when combined, form a single 

piece of territory. Noncontinuous areas 

form disjoint pieces. 

Great Lakes’ waters—Water area 

beyond one mile wide headland 

embayments located in any of the five 

Great Lakes: Erie, Huron, Michigan, 

Ontario, or Superior. 

Group quarters (GQ)—A place where 

people live or stay, in a group living 

arrangement, that is owned or managed 

by an entity or organization providing 

housing and/or services for the 

residents. This is not a typical 

household-type living arrangement. 

These services may include custodial or 

medical care, as well as other types of 

assistance, and residency is commonly 

restricted to those receiving these 

services. People living in group quarters 

are usually not related to each other. 

Group quarters include such places as 

college residence halls, residential 

treatment centers, skilled nursing 

facilities, group homes, military 

barracks, correctional facilities, and 

workers’ dormitories. 

Incorporated place—A type of 

governmental unit, incorporated under 

state law as a city, town (except in New 

England, New York, and Wisconsin), 

borough (except in Alaska and New 

York), or village, generally to provide 

governmental services for a 

concentration of people within legally 

prescribed boundaries. 

Inland water—Water bodies entirely 

surrounded by land or at the point 

where their opening to coastal waters, 

territorial seas, or the Great Lakes is less 

than one mile across. 

Minor civil division (MCD)—The 

primary governmental or administrative 

division of a county in 28 states and the 

Island Areas having legal boundaries, 

names, and descriptions. MCDs 

represent many different types of legal 

entities with a wide variety of 

characteristics, powers, and functions 

depending on the state and type of 

MCD. In some states, some or all of the 

incorporated places also constitute 

MCDs. 

Nonvisible feature—A map feature 

that is not visible on the ground, such 

as a city or county boundary through 

space, a property line, line-of-sight 

extension of a road. 

Special land use block group—Block 

group delineated coextensive with, or 

covering the same area as, the special 

land use tract. 

Special land use tract—Type of 

census tract that must be designated as 

a specific land use type (e.g. state park) 

and have an official name (e.g., Jay 

Cooke State Park), must have little or no 

residential population or housing units, 

and must not create a noncontiguous 

census tract. If delineated in a densely 

populated, urban area, a special land 

use tract must have an area of 

approximately one square mile or more. 

If delineated completely outside an 

urban area, a special land use tract must 

have an area of approximately 10 square 

miles or more. 

Territorial seas—Water bodies not 

included under the definition for inland 

water, coastal water, or Great Lakes’

waters, see above. 

TIGER—Topologically Integrated 

Geographic Encoding and Referencing 

database developed by the Census 

Bureau to support its mapping needs for 

the Decennial Census and other Census 

Bureau programs. The topological 

structure of the TIGER database defines 

the location and relationship of 

boundaries, streets, rivers, railroads, and 

other features to each other and to the 

numerous geographic areas for which 

the Census Bureau tabulates data from 

its censuses and surveys. 

Visible feature—A map feature that 

can be seen on the ground, such as a 

road, railroad track, major above-ground 

transmission line or pipeline, river or 

stream, shoreline, fence, sharply defined 

mountain ridge, or cliff. A nonstandard 

visible feature is a feature that may not 

be clearly defined on the ground (such 

as a ridge), may be seasonal (such as an 

intermittent stream), or may be 

relatively impermanent (such as a 

fence). The Census Bureau generally 

requests verification that nonstandard 

features used as boundaries for the 

PSAP geographic areas pose no problem 

in their location during field work. 

Water body block group—Block group 

delineated coextensive with, or covering 

the same area as, the water body tract. 


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Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 17343 

Water body tract—Type of census 

tract encompassing territorial seas, 

coastal water, the Great Lakes, or inland 

water at least 100 square miles in area. 

If an inland water body meets this 

criteria, each county can delineate a 

census tract for its portion of the water 

body. 

Executive Order 12866 

This notice has been determined to be 

not significant under Executive Order 

12866. 

Paperwork Reduction Act 

This program notice does not 

represent a collection of information 

subject to the requirements of the 

Paperwork Reduction Act, 44 U.S.C. 

Chapter 35. 

Dated: April 3, 2007. 

Charles Louis Kincannon, 

Director, Bureau of the Census. 

[FR Doc. E7–6467 Filed 4–5–07; 8:45 am] 

BILLING CODE 3510–07–P 


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