Block Group Program for Census 2000Proposed Criteria

DEPARTMENT OF COMMERCE

Bureau of the Census

[Docket No. 970408082-7082-01]

RIN 0607-XX28

Block Group Program for Census 2000--Proposed Criteria

AGENCY: Bureau of the Census, Commerce.

ACTION: Notice of proposed program revisions and request for comments.

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SUMMARY: Block groups are geographic statistical divisions of census

tracts, each of which consists of from one to nine block groups. A

block group comprises a reasonably compact and contiguous cluster of

census blocks. The primary goal of the block group program is to

provide data users with a geographic subunit of census tracts for which

decennial census sample and 100 percent data are tabulated and

disseminated.

The Census Bureau first used block groups in its data presentations

from the 1970 census. It did this in lieu of providing data summaries

for enumeration districts in areas that had census block numbers. As

census blocks and block groups became increasingly popular with data

users, the Census Bureau established them in many new areas. By 1990,

there was complete census block and block group coverage for all of the

United States, Puerto Rico, and the Island Areas (American Samoa, Guam,

the Northern Mariana Islands, and the Virgin Islands of the United

States).

Through the 1990 census, block groups were subunits either of

census tracts or of similar entities known as block numbering areas

(BNAs). For areas where census tracts did not exist, the Census Bureau

had established BNAs to control the numbering of census blocks within

block groups. A county or statistically equivalent entity 1

could, therefore, have either census tracts or BNAs. For Census 2000,

the Census Bureau will merge the two programs and convert all BNAs to

census tracts.

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\1\ Includes parishes in Louisiana; boroughs and census areas in

Alaska; independent cities in Maryland, Missouri, Nevada, and

Virginia; that portion of Yellowstone National Park in Montana;

districts in American Samoa and the Virgin Islands of the United

States; municipalities in the Northern Mariana Islands; municipios

in Puerto Rico; and the entire areas constituting the District of

Columbia and Guam. This notice will refer to all these entities

collectively as ``counties.''

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To determine boundaries and identification numbers for block

groups, the Census Bureau offers a program to local participants, such

as locally identified agencies and American Indian tribal officials,

whereby they can review and update the boundaries of the block groups

delineated for the 1990 census and suggest revisions according to the

criteria developed and promulgated by the Census Bureau. The Census

Bureau then reviews the resulting block groups for conformance to these

criteria.

As the first step in this process, the Census Bureau is requesting

comments on the criteria proposed for the delineation of block groups

in conjunction with Census 2000. These criteria will apply to the 50

states, American Indian and Alaska Native areas, Puerto Rico, and the

Island Areas. The Census Bureau may modify and, if

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necessary, reject proposals for block groups that do not meet the

criteria established following this notice.

Besides the proposed criteria, this notice includes a description

of the changes from the criteria used for the 1990 census and a list of

definitions of key terms used in the criteria.

DATES: Any suggestions or recommendations concerning the proposed

criteria should be submitted in writing by June 2, 1997.

ADDRESSES: Director, Bureau of the Census, Washington, DC 20233-0001.

FOR FURTHER INFORMATION CONTACT: Dr. Joel Morrison, Chief, Geography

Division, Bureau of the Census, Washington, DC 20233-7400, telephone

(301) 457-1132, or e-mail ([email protected]).

SUPPLEMENTARY INFORMATION: The block group delineation criteria have

evolved in response to decennial census practices and the preferences

of program participants and data users. After each decennial census,

the Census Bureau, in consultation with participants and data users,

reviews and revises these criteria. Then, before the next decennial

census, the Census Bureau offers state, tribal, and local officials an

opportunity to correct, update, and otherwise improve the block group

delineations.

In July and August 1995, the Census Bureau issued invitations to

local and tribal groups and agencies to participate in the delineation

of statistical geographic areas for Census 2000. These included

regional planning agencies, councils of governments, county planning

agencies, officials of Federally recognized American Indian tribes, and

officials of the 12 nonprofit Alaska Native Regional Corporations.

During 1997, the Census Bureau will provide materials and detailed

guidelines to program participants for the review and delineation of

block groups for Census 2000.

A. Criteria For Delineating Block Groups For Census 2000

The Census Bureau proposes the following criteria for use in

delineating Census 2000 block groups.

1. General Characteristics

A block group must meet the population and boundary

feature criteria and comprise a compact piece of territory.

A census tract boundary always must be a block group

boundary.

Each census tract must contain a minimum of one block

group and may have a maximum of nine block groups.

Block groups must cover the entire land and inland water

area of a census tract.

A block group entirely within an American Indian

reservation (AIR) may extend across a state or county boundary for

tabulations in the American Indian geographic hierarchy. For standard

data tabulations, the portion of the block group in each state and

county is treated as a separate block group.

2. Identification

A block group consists of all blocks within a census tract

that have the same first digit and is identified using that same first

digit. For example in 1990, block group 3 included all census blocks

numbered in the 300s. For Census 2000, the Census Bureau will introduce

a four-digit block numbering system, and block group 3 will include all

census blocks numbered in the 3000s within a census tract.

The range of acceptable block group numbers is 1 through

9. Block group numbers must always be unique within a census tract;

that is, the same number cannot be repeated.

The Census Bureau will assign a single ``zero'' block

group to census tracts numbered ``0000.'' (In counties that have

coastal water, territorial sea, or Great Lakes waters, the Census

Bureau recommends establishing a ``0000'' census tract to provide

complete area coverage.)

3. Boundary Features

The Census Bureau recommends that block group boundaries follow

visible and identifiable features; that is, visible, perennial natural

and cultural features such as roads, rivers, canals, railroads, above-

ground high-tension power lines, and so forth. This provision makes the

location of boundaries less ambiguous and easier for data users to

locate.

State and county boundaries are always block group boundaries. The

Census Bureau also permits the use of other types of legal boundaries

in some states and situations where the boundaries of these

governmental units tend to remain unchanged between censuses. The

following features are acceptable as block group boundaries:

All minor civil division (MCD) boundaries (generally towns

or townships) in Connecticut, Indiana, Maine, Massachusetts, New

Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and

Vermont.

Those MCD boundaries not conjoint with the boundaries of

incorporated places that themselves are MCDs (being either coextensive

with or independent of MCDs) in Illinois (townships only, not election

precincts), Iowa, Kansas, Michigan, Minnesota, Missouri (governmental

townships only), Nebraska (townships only, not election precincts),

North Dakota, Ohio, South Dakota, and Wisconsin.

Barrio, barrio-pueblo, and subbarrio boundaries in Puerto

Rico, census subdistrict boundaries in the Virgin Islands of the United

States, MCD-county and island boundaries in American Samoa, and

municipal district boundaries in the Northern Mariana Islands.

All incorporated place boundaries in Connecticut, Maine,

Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode

Island, and Vermont.

Conjoint incorporated place boundaries in other states;

that is, the boundary separating two different incorporated places.

AIR boundaries.

American Indian trust land, Alaska Native village

statistical area, and Alaska Native Regional Corporation boundaries, at

the discretion of the Census Bureau, insofar as such boundaries are

unambiguous for allocating living quarters as part of census

activities.

When the above types of features are not available for selection,

the Census Bureau may, at its discretion, approve other nonstandard

visible features, such as ridge lines, pipelines, intermittent streams,

fence lines, and so forth. The Census Bureau also may accept, on a

case-by-case basis, the boundaries of selected nonstandard and

potentially nonvisible features, such as the boundaries of national

parks and forests, cemeteries, or other special land-use properties,

the straight-line extensions of visible features, and other lines of

sight.

4. Population Thresholds

The Census Bureau proposes standard size criteria for most block

groups in the United States, Puerto Rico, and the Island Areas (see

Table 1). Smaller optimum and minimum sizes are permissible for block

groups located on AIRs or comprising special places. (Special places

are correctional institutions, military installations, college

campuses, workers' dormitories, hospitals, nursing homes, and group

homes.)

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Table 1.--Population Thresholds for Census 2000 Block Groups

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Area(s) Optimum Minimum Maximum

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Standard (most areas).................................................... 1,500 600 3,000

AIRs..................................................................... 1,000 300 3,000

Special place block group................................................ none 300 none

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If a block group located on an AIR crosses a county boundary or a

state boundary, the minimum population size criterion applies to the

entire area of the block group, not to the individual portions that are

in separate counties or states.

5. Final Approval of Block Groups

The Census Bureau reserves the right to approve all block group

proposals for Census 2000. The Census Bureau will make an effort to

reach agreement with local and tribal participants in the block group

program, but cannot approve the use of block groups as submitted if

they do not meet Census 2000 criteria. If necessary, the Census Bureau

will revise block group boundaries where they do not meet the boundary

and population size requirements.

B. Changes to the Criteria for Census 2000

Most provisions of the block group criteria remain unchanged from

those used in conjunction with the 1990 census, with the few exceptions

summarized below:

1. For 1990 and previous decennial censuses, the Census Bureau

delineated the block groups in BNAs on the basis of the number of

housing units rather than population. For Census 2000, the Census

Bureau is merging the census tract and BNA programs to create a single

census tract program, and the size criteria for all block groups will

be on the basis of population rather than the number of housing units.

2. For Census 2000, the Census Bureau is increasing the number of

governmental units that have boundaries acceptable to use as block

group boundaries. The added areas are: All MCDs in Indiana and selected

MCDs in Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri,

Nebraska, North Dakota, South Dakota, and Wisconsin; the MCD-county and

island areas of American Samoa; and villages in New York.

3. The Census Bureau now allows officials of Federally recognized

AIRs to establish block groups that cross state or county boundaries.

While the Census Bureau will publish data for each state-county-census

tract-block group part, it also plans to provide summed data for all

block groups that are located within an AIR and that cross state or

county boundaries.

Definitions of Key Terms

Alaska Native Regional Corporation (ANRC)--A corporate entity

established under the Alaska Native Claims Settlement Act of 1972, Pub.

L. 92-203, as amended by Pub. L. 92-204, to conduct both the business

and nonprofit affairs of Alaska Natives. Twelve ANRCs cover the entire

State of Alaska except for the Annette Islands Reserve.

Alaska Native village statistical area (ANVSA)--A statistical

entity containing the densely settled extent of an Alaska Native

village that constitutes an association, band, clan, community, group,

tribe, or village recognized pursuant to the Alaska Native Claims

Settlement Act of 1972, Pub. L. 92-203, as amended by Pub. L. 92-204.

American Indian reservation (AIR)--A Federally recognized American

Indian entity with boundaries established by treaty, statute, and/or

executive or court order and over which American Indians have

governmental jurisdiction. Along with reservation, designations such as

colonies, communities, pueblos, rancherias, and reserves apply to AIRs.

Block numbering area (BNA)--A small-area, statistical geographic

division of a county or statistically equivalent area delineated in

1990 instead of and generally geographically equivalent to a census

tract. For Census 2000, the Census Bureau is merging the BNA program

with the census tract program and converting all BNAs to census tracts.

Census block--The smallest geographic entity for which the Census

Bureau collects and tabulates decennial census information; bounded on

all sides by visible and nonvisible features identified by the Census

Bureau in computer files and on maps.

Census tract--A small, relatively permanent statistical geographic

subdivision of a county or statistically equivalent area defined for

the tabulation of data. For Census 2000, the Census Bureau is replacing

BNAs with census tracts.

Coastal water--Water bodies between territorial seas and inland

water, the encompassing headlands being greater than one mile apart and

less than 24 miles apart.

Conjoint--A description of a boundary shared by two adjacent

geographic areas.

Contiguous--A description of geographic areas that are adjacent to

one another, sharing either a common boundary or point.

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.

Incorporated place--A type of governmental unit, sanctioned by

state law as a city, town (except in New England, New York, and

Wisconsin), village, or borough (except in Alaska and New York), having

legally prescribed limits, powers, and functions.

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, Puerto Rico, 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, a short line-of-sight extension of a road, or a point-to-point

line of sight.

Special place--A specific location requiring special enumeration

procedures because the location includes people not in households or

the area includes special land use. Special places include facilities

with resident population, such as correctional institutions, military

installations, college campuses, workers' dormitories, hospitals,

nursing homes and group homes and land-use areas such as national

parks. A special place includes the entire facility, including

nonresidential areas and staff

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housing units, as well as all group quarters population.

Territorial seas--Water bodies not included under the rules for

inland water, coastal water, or Great Lakes waters (see above).

Visible feature--A map feature that one can see on the ground such

as a road, railroad track, above-ground transmission line, 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.

Dated: April 1, 1997.

Martha Farnsworth Riche,

Director, Bureau of the Census.

[FR Doc. 97-11453 Filed 5-1-97; 8:45 am]

BILLING CODE 3510-07-P