Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 17329 

1 Includes parishes in Louisiana; boroughs, city 

and boroughs, census areas, and municipalities in 

Alaska; independent cities in Maryland, Missouri, 

Nevada, and Virginia; districts in American Samoa 

and the U.S. Virgin Islands; municipalities in the 

Commonwealth of the Northern Mariana Islands; 

municipios in Puerto Rico; the areas constituting 

the District of Columbia and Guam. This notice will 

refer to all these entities collectively as ‘‘counties.’’

2The ACS is conducted in the United States and 

in Puerto Rico. In Puerto Rico the survey is called 

the Puerto Rico Community Survey (PRCS). 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. 

3For Census Bureau purposes, the United States 

includes the fifty States and the District of 

Columbia. 

4The 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 

(CDPs), and, if these areas have a population of 

2,400 or greater, may delineate tribal tracts and 

tribal block groups for their reservation and offreservation trust land. 

5For 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. 

boundaries of UAs at the time of each 

decennial census or from the results of 

a special census during the intercensal 

period. 

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, 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 pose no problem in their 

location during field work. 

Zona urbana—In Puerto Rico, the 

settled area functioning as the seat of 

government for a municipio. A zona 

urbana cannot cross a municipio 

boundary. 

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. E7–6465 Filed 4–5–07; 8:45 am] 

BILLING CODE 3510–07–P 

DEPARTMENT OF COMMERCE 

Bureau of the Census 

[Docket Number 070321065–7066–01] 

Census Tract Program for the 2010 

Census—Proposed Criteria 

AGENCY: Bureau of the Census, 

Commerce. 

ACTION: Notice of proposed program 

revisions and request for comments. 

SUMMARY: Census tracts are relatively 

permanent small-area geographic 

divisions of a county or statistically 

equivalent entity 1 defined for the 

tabulation of decennial census data and 

selected other statistical programs. 

Census tracts also will be used to 

tabulate and publish estimates from the 

American Community Survey (ACS) 2

after 2010. 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. 

Most provisions of the census tract 

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) Lowering the 

minimum population threshold for 

census tracts; (2) using housing unit 

counts (as an alternative to population 

counts) in the review and update of 

tracts; (3) applying the same population 

and housing unit thresholds to all types 

of populated tracts within the United 

States,3 including census tracts 

delineated on American Indian 

reservations and off-reservation trust 

lands,4 Puerto Rico, the Island Areas,5

and encompassing group quarters, 

military installations, and institutions; 

(4) allowing the delineation of census 

tracts for large water bodies with areas 

of approximately 100 square miles or 

more and special land use (e.g., large 

airports or public parks) with an official 

name; and (5) allowing for geographic 

frameworks of tribal tracts (separate 

from the standard census tracts defined 

within counties) to be defined within 

federally-recognized American Indian 

reservations and off-reservation trust 

lands. 

In addition to 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 (e.g., tract 

code) of the census tracts in their 

geographic area under the Participant 

Statistical Areas Program (PSAP). In 

addition to census tracts, the program 

also encompasses the review and update 

of block groups, 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 Census Tracts 

In 1905, Dr. Walter Laidlaw originated 

the concept of permanent, small 

geographic areas as a framework for 

studying change from one decennial 

census to another in neighborhoods 

within New York City. For the 1910 

Census, eight cities—New York, 

Baltimore, Boston, Chicago, Cleveland, 

Philadelphia, Pittsburgh, and St. 

Louis—delineated census tracts (then 

termed ‘‘districts’’) for the first time. No 

additional jurisdictions delineated 

census tracts until just prior to the 1930 

Census, when an additional ten cities 

chose to do so. The increased interest in 

census tracts for the 1930 Census is 

attributed to the promotional efforts of 

Howard Whipple Green, who was a 

statistician in Cleveland, Ohio, and later 

the chairman of the American Statistical 

Association’s Committee on Census 

Enumeration Areas. For more than 


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twenty-five years, Mr. Green strongly 

encouraged local citizens, via 

committees, to establish census tracts 

and other census statistical geographic 

areas. The committees created by local 

citizens were known as Census Tract 

Committees, later called Census 

Statistical Areas Committees. 

After 1930, the Census Bureau saw 

the need to standardize the delineation, 

review, and updating of census tracts 

and published the first set of census 

tract criteria in 1934. The goal of the 

criteria has remained unchanged; that 

is, to assure comparability and data 

reliability through the standardization 

of the population thresholds for census 

tracts, as well as requiring that their 

boundaries follow specific types of 

geographic features that do not change 

frequently. The Census Bureau began 

publishing census tract data as part of 

its standard tabulations beginning with 

the 1940 Census. Prior to that time, 

census tract data were published as 

special tabulations. 

For the 1940 Census, the Census 

Bureau began publishing census block 

data for all cities with 50,000 or more 

people. Census block numbers were 

assigned, where possible, by census 

tract, but for those cities that had not yet 

delineated census tracts, ‘‘block areas’’

(called ‘‘block numbering areas’’ [BNAs] 

in later censuses) were created to assign 

census block numbers. 

Starting with the 1960 Census, the 

Census Bureau assumed a greater role in 

promoting and coordinating the 

delineation, review, and update of 

census tracts. For the 1980 Census, 

criteria for BNAs were changed to make 

them more comparable in size and 

shape to census tracts. For the 1990 

Census, all counties contained either 

census tracts or BNAs. 

Census 2000 was the first decade in 

which census tracts were defined in all 

counties. In addition, the Census Bureau 

increased the number of geographic 

areas whose boundaries could be used 

as census tract boundaries. It also 

allowed tribal governments of federally 

recognized American Indian tribes with 

a reservation and/or off-reservation trust 

lands to delineate tracts 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 

Census Tracts for the 2010 Census 

A. General Principles 

1. 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. Comparability 

has always been a goal in the census 

tract program since its inception for the 

1910 census; however, as the use of tract 

data increases, the importance of 

comparability increases as well. 

Maintaining comparability of tract 

boundaries over time facilitates 

longitudinal data analysis. The advent 

of the ACS and the averaging of sample 

data for tracts over a five-year span 

further underscore the need for 

consistent tract boundaries over time. 

Pursuant to this goal of continuity and 

comparability, the Census Bureau 

requests that where a census tract must 

be updated, for example to meet the 

minimum or maximum population or 

housing unit thresholds, that the outer 

boundaries of the tract not be changed, 

but rather that a tract be split into two 

or more tracts, or merged 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-bycase basis. 

2. 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 may have the 

effect of restricting the availability and 

amount of sample data published for 

geographic areas with small 

populations. Aiming to create census 

tracts that meet the optimal population 

of 4,000 and maintaining minimum 

thresholds will improve the reliability 

and availability of data, and local 

governments and planners should 

consider these factors when defining 

their census tracts. Therefore, the 

Census Bureau proposes that any census 

tracts not flagged as a water body or 

special land use tract (General Principle 

4) must encompass at least 1,200 people 

or at least 480 housing units. 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 1). 

The Census Bureau will use Census 

2000 population and housing unit 

counts, with allowance made for growth 

since 2000, to assess whether each 

census tract submitted meets this 

criterion. Program participants may 

submit local estimates as a surrogate for 

the Census 2000 population and 

housing unit counts for a census tract. 


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3. With the advent of the ACS and the 

‘‘continuous measurement’’ of 

characteristics of the population and 

housing based on a five-year average, 

there are some new issues to consider in 

the census tract criteria. The Census 

Bureau proposes the use of either 

population or housing units in the 

review of census tracts. The ACS is 

designed to produce local area data as 

of a 12-month period estimate (or an 

average); whereas, in the past local area 

data were represented as of the April 1 

census day. 

4. The Census Bureau recognizes that 

there are geographic areas that are not 

characterized by a residential 

population, and which local 

participants may wish to separate from 

populated tracts for analytical or 

cartographic purposes or both. The 

Census Bureau proposes identifying 

these areas as water body tracts and 

special land use tracts. Special land use 

tracts must be designated as a specific 

type of land use (e.g., State park, 

municipal park) and have an official 

name, generally have little or no 

residential population or housing units, 

and must not create a noncontiguous 

census tract. If located in a densely 

populated urban area, a special land use 

tract must have an area of 

approximately 1 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. The Census Bureau 

recognizes that some special land use 

areas not 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 tracts 

and therefore will accept such areas as 

tracts even if some residential 

population is present. 

5. 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 

and/or off-reservation trust lands. Each 

contiguous American Indian reservation 

and/or off-reservation trust land should 

be included, along with any necessary 

territory outside the reservation and/or 

off-reservation trust land, within a 

single census tract or as few census 

tracts as possible for the 2010 Census. 

This is the only situation in which 

retracting is encouraged. See, for 

example, Figure 2 below. 


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17332 Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 

B. Changes to the Census Tract Criteria 

for the 2010 Census 

Most provisions of the census tract 

criteria for the 2010 Census would 

remain unchanged from those used in 

conjunction with Census 2000 with only 

the following exceptions: 

1. The minimum population 

threshold for census tracts would be 

1,200, lowered from the minimum 

threshold of 1,500 used in Census 2000. 

This change seeks to create a standard 

minimum threshold for census block 

groups and census tracts, in order to 

support the reliability and availability of 

sample data for these statistical 

geographies. 

2. Housing unit counts may be used 

instead of population counts in the 

review and update of tracts. This change 

seeks to accommodate 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. 

3. For Census 2000, minimum 

population thresholds for census tracts 

varied. The minimum population 

threshold for census tracts delineated on 

American Indian reservations and offreservation trust lands was 1,000. This 

differed from the minimum threshold of 

1,500 people for census tracts defined 

elsewhere in the United States, as well 

as in Puerto Rico and the Island Areas. 

Optimum populations for census tracts 

also varied: 4,000 in the United States 

and Puerto Rico, and 2,500 on American 

Indian reservations and in the Island 

Areas. The maximum population for a 

census tract in any of these areas was 

8,000. In addition, for Census 2000, 

tracts that enclosed an institution, a 

military installation, or other ‘‘special 

place’’ had a minimum population 

requirement of 1,000 inhabitants, with 

no optimum or maximum. 

For the 2010 Census the same 

population and housing unit thresholds 

would apply to all types of populated 

tracts, including census tracts 

delineated on 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 tracts and to 

create a single national standard. 

4. The delineation of census tracts 

would be permitted, and encouraged, 

for the following types of geographic 

areas: 

a. Large water bodies with areas of 

approximately 100 square miles or 

more. 

b. Special land uses (for example, 

large airports, public parks, or public 

forests) with an official name. 

The Census Bureau would require 

that special land use tracts have little or 

no residential population. All such 

census tracts would meet all other tract 

criteria. 

5. A geographic framework of tribal 

tracts, separate from the standard census 

tracts defined within counties, may be 

defined within federally recognized 

American Indian reservations and/or 

off-reservation trust lands, subject to 

other population, housing, and 

boundary criteria contained in this 

document. This represents a change 

from the practice for Census 2000. The 

Census Bureau proposes this change to 

better recognize the unique statistical 

data needs of federally recognized 

American Indian tribes and their 

reservation and off-reservation trust 

lands. 

C. Census Tract 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. 

The Census Bureau may modify and, if 

necessary, reject any proposals for 

census tracts that do not meet the 

established criteria. In addition, the 

Census Bureau reserves the right to 

modify the boundaries and attributes of 

tracts 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 reviewing 

2010 Census tracts: 

1. A census tract must comprise a 

reasonably compact and contiguous 

land area. 

Noncontiguous boundaries are 

permitted only where a noncontiguous 

area or inaccessible area would not meet 

population or housing unit count 

requirements for a separate tract, in 

which case the noncontiguous or 

inaccessible area must be included 

within an adjacent or proximate tract. 

For example, an island that does not 

meet the minimum population 


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threshold for recognition as a separate 

tract should be combined with other 

proximate land to form a single tract. 

Each case will be reviewed and 

accepted at the Census Bureau’s 

discretion. 

2. A census tract must cover the entire 

land and water area of a 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 should be created for each discrete 

water body to provide for complete 

census tract coverage. 

3. 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 

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 

tract boundaries over time, as the 

locations of many visible features in the 

landscape tend to change infrequently. 

The following features are preferred 

as census tract boundaries for the 2010 

Census: 

a. State and county boundaries must 

always be tract boundaries. This 

criterion takes precedence over all other 

criteria or requirements except for the 

population threshold criteria for tribal 

tracts on American Indian reservations 

and/or off-reservation trust lands. 

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 tract boundaries. 

TABLE 1.—ACCEPTABLE MCD AND INCORPORATED PLACE 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 

places 

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 

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 


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

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 

places 

boundaries 

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 census tract 

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 tract boundaries, the 

Census Bureau may, at its discretion, 

approve other nonstandard visible 

features, such as ridge lines, aboveground 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, or 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, large airports, 

and military installations, provided the 

boundaries are clearly marked or easily 

recognized. 

4. Population, Housing Unit, and Area 

Thresholds 

The Census Bureau proposes the 

following population, housing unit, and 

area threshold criteria for census tracts 

(as summarized in Table 2). 

TABLE 2.—TRACT THRESHOLDS

Tract type Threshold type Optimum Minimum Maximum 

Standard & tribal tracts .............................. Population threshold ................................. 4,000 ....................... 1,200 8,000 

Housing Unit threshold .............................. 1,600 ....................... 480 3,200 

Water body tracts ....................................... Area threshold (square miles) ................... none ........................ 100 none 

Special land use tracts .............................. Area threshold for an urban area (square 

miles).

none ........................ 1 none 

Area threshold outside an urban area 

(square miles).

none ........................ 10 none 

a. Population counts should be used 

in tract review in most cases. Housing 

unit counts should be used for 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 tracts, 

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 tract proposals. 

c. The Census Bureau recognizes the 

tension that exists between meeting the 

optimum population or housing unit 

threshold in a tract and maintaining 

tract comparability over time. For 

example, if population growth has 

occurred since 2000 or is expected 

before 2010 for a census tract, the tract 

should not be merged if it has a Census 

2000 population of at least 1,100 or a 

housing unit count of at least 440 and 

acceptable supporting evidence is 

supplied by the PSAP participant that 

population and/or housing unit growth 

has occurred since Census 2000, or will 

likely occur before 2010, and has been 

sufficient to meet the minimum 

thresholds. However, should the census 

tract’s population not increase as 

expected and does not meet either of the 

minimum thresholds in 2010, this may 

adversely affect the reliability and 

availability of any sample estimates for 

that tract. For this reason, the Census 

Bureau suggests merging the census 

tract with another if there is a 

possibility that anticipated growth will 

not be sufficient to meet minimum 

thresholds. 


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d. The Census Bureau may waive the 

maximum population and housing 

thresholds as required to achieve the 

objectives of this notice. 

e. For the 2010 Census, the Census 

Bureau encourages the delineation of 

special-use tracts in specific types of 

areas. 

i. A special land use tract 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 tract. 

In some instances, multiple areas can be 

combined to form a single special landuse tract if the land management 

characteristics are similar, such as a 

special land-use tract comprising 

adjacent Federal and State parks. If the 

special land use tract is delineated in a 

densely populated, urban area, the tract 

must have an area of approximately one 

square mile or more. If the special landuse tract is delineated completely 

outside an urban area, the tract must 

have an area of approximately 10 square 

miles or more. 

ii. A water body tract 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 a water body meets this criterion and 

is in more than one county, each county 

can delineate a tract for its portion of 

the water body. Any islands within a 

qualifying water body should be 

included within a separate tract. 

5. Identification of Census Tracts 

a. A census tract has a basic census 

tract identifier composed of no more 

than four digits and may have a twodigit decimal suffix. 

b. The range of acceptable basic 

census tract identifiers for the 2010 

Census is from 1 to 9949 (but, see 5.c. 

below); tracts delineated specifically to 

complete coverage of large water bodies 

will be numbered from 9950 to 9989 in 

each county. All other tracts that fall 

within the 9950–9989 range must be 

renumbered. For Census 2000, water 

body tracts were all coded 0000. Each of 

these must be renumbered for the 2010 

Census. 

c. Census tracts delineated within or 

to primarily encompass American 

Indian reservations and/or offreservation trust lands can continue to 

be numbered from 9400 to 9499. Local 

participants may opt to renumber these 

census tracts in a numeric range 

consistent with the rest of the county 

since tribal tracts are proposed to be a 

separate and distinct geographic entity. 

d. Census tract identifiers must be 

unique within each county. 

e. Once used, census tract identifiers 

cannot be reused in a subsequent census 

to reference a completely different area 

within a county. If a 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 Census 2000 is 

split, each portion must be given a new 

suffix. 

f. The range of acceptable census tract 

suffixes is .01 to .98. 

6. Census Tract types 

Table 3 below contains a summary of 

the types of census tracts (with their 

respective population, housing unit and 

area characteristics) that the Census 

Bureau proposes to use for the 2010 

Census. 

TABLE 3.—SUMMARY OF CENSUS TRACT TYPES

How distinct from standard census 

tracts 

Population thresholds Housing unit 

thresholds Area thresholds 

Standard & tribal 

tracts.

Tribal tracts are conceptually similar 

and equivalent to census tracts defined within the standard Statecounty-tract-block group geographic 

hierarchy used for tabulating and 

publishing statistical data.

Optimum: 4,000; ...

Minimum: 1,200; ...

Maximum: 8,000 ...

Optimum: 1,600; 

Minimum: 480; ......

Maximum: 3,200 ...

None. 

Water body tract .... A tract encompassing all or part of a 

territorial sea, coastal water, a 

Great Lake, or an inland water body 

at least 100 square miles in area.

Zero ...................... Zero ...................... 100 square miles if an inland water 

body. 

Special land-use 

tract.

A 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 tract 

should be approximately 1 square 

mile in area or greater. If delineated 

completely outside an urban area, a 

special land-use tract should have 

an area of 10 square miles or greater.

Little or none ........ Little or none ........ 1 square mile within an urban area/10 

square miles outside an urban area. 

D. Tribal Tracts 

Tribal 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 American Indian reservation 

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 tracts allows for an 

unambiguous presentation of tract-level 

data specific to the American Indian 

reservations and/or off-reservation trust 

lands without the imposition of State or 

county boundaries, which might 

artificially separate American Indian 

populations located within a single 

reservation and/or off-reservation trust 

land. To this end, the American Indian 

tribal participant may define tribal tracts 

that cross county or State boundaries, or 

both. For federally recognized American 

Indian tribes with reservations and/or 

off-reservation trust lands that have 

more than 2,400 residents, the Census 

Bureau will offer the tribal government 

the opportunity to delineate tribal tracts 

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 


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17336 Federal Register / Vol. 72, No. 66 / Friday, April 6, 2007 / Notices 

lands that have fewer than 2,400 

residents, the Census Bureau will define 

one tribal tract and one tribal block 

group coextensive with the reservation 

and/or off-reservation trust land. Tribal 

tracts must be delineated to meet all 

other census tract criteria, and must be 

numbered uniquely so as to clearly 

distinguish them from county-based 

census tracts. Tribal tracts are 

conceptually similar and equivalent to 

census tracts 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 to make meaningful and 

reliable data available for these areas 

and their populations, the Census 

Bureau proposes that for the 2010 

Census, standard census tracts be 

delineated nationwide, and the tribal 

tract 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 tracts were defined 

for federally recognized American 

Indian reservations and/or offreservation trust lands 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-countycensus tract hierarchy was maintained, 

even for territory contained within an 

American Indian reservation and/or offreservation trust land. 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 

or housing unit thresholds, therefore 

potentially limiting sample data 

reliability or availability for both the 

tribal tract and the derived standard 

tracts. The proposed change in the tribal 

tract program for the 2010 Census, 

creating standard, county-based census 

tracts nationwide and maintaining tribal 

tracts as a completely separate set of 

geography from standard tracts for both 

geographic information and data 

presentation purposes, seeks to 

eliminate, in part, these issues that 

existed with Census 2000 data. 

As with standard census tracts 

submitted through this program, the 

tribal tracts would be submitted to the 

Census Bureau, and would be subject to 

review to ensure compliance with the 

final published criteria. Tribal tracts 

will be defined as part of a separate 

Tribal Statistical Areas Program (TSAP) 

for the 2010 Census. Detailed criteria 

pertaining to tribal tracts 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—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. Noncontiguous 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—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. The 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, or line-of-sight 

extension of a road. 

Retracting—Substantially changing 

the boundaries of a tract so that 

comparability over time is not 

maintained. 

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 

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 rules 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 


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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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