U.S. Census Resources on the Web
Alphabetical List of Geography Terms
1990 Census of Population & Housing

Below are definitions of some common geographic terms used with the 1990 Census of Population and Housing. The definitions are fairly broad. For more precise definitions, please see the documentation for the Census report or database you're using.

This list is arranged in alphabetical order. If you'd like to see definitions of these terms in relation to one another, see the guide 1990 Census of Population & Housing Geography Terms, which illustrates some of the geographic hierarchies (groupings of geographic units) that are used in the 1990 Census of Population and Housing.

Jump to terms starting with: A - B C D - I J - L M N - O P - R S - T U W - Z


American Indian reservations: see Federal American Indian reservations or State [Indian] Reservations.


Block: small area bounded on all sides by visible features such as streets, roads, streams, and railroad tracks, and by invisible boundaries such as city, town, township, and county limits, and property lines. The entire country was "blocked" for the 1990 Census. (Sample data not available for blocks.)

Block group (BG): group of blocks within a census tract or block numbering area (BNA). BGs generally contain between 250 and 550 housing units, with the ideal size being 400 housing units.

Block numbering area (BNA): small statistical subdivision of a county for grouping and numbering blocks in non-metropolitan counties.

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Census county divisions (CCDs): subdivisions of a county where minor civil divisions(MCDs) are not established or change frequently. Defined by Census and local officials for statistical purposes. CCDs have no legal functions, and are not governmental units.

Census designated places (CDPs): densely settled concentration of population that are identifiable by name, but are not legally incorporated places. For decennial census purposes, the statistical counterparts of incorporated places.

Census subareas: statistical subdivisions of census areas (Alaska only) and boroughs.

Central City: in each Metropolitan Statistical Area and Consolidated Metropolitan Statistical Area, the largest place and, in some cases, additional places are designated as "central cities" under the official standards.

Central Place: See Urbanized Area Central Place.

Consolidated Metropolitan Statistical Area (CMSA): two or more contiguous Metropolitan Areas.

County: the primary political divisions of most states, including Wisconsin.

County equivalent: geographic entity not legally referred to as a county but treated as such for data tabulation purposes (example: parishes in Louisiana).

County subdivisions: primary subdivision of counties and their equivalents for the reporting of decennial census data. The most common county subdivisions are minor civil divisions. Other county subdivisions include census county divisions, census subareas, and unorganized territories.

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D - I

Division: subdivisions of Census regions. There are a total of nine divisions.

Federal American Indian reservations: areas with boundaries established by treaty, statute, and/or executive or court order, and recognized by the Federal Government as territory in which American Indian tribes have jurisdiction.

Incorporated places: legally incorporated cities, boroughs, towns, or villages (with some exceptions, depending on the state). In Wisconsin, incorporated places include cities and villages, not towns (towns are considered minor civil divisions).

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Metropolitan Area (MA): a large population nucleus, together with adjacent communities that have a high degree of economic and social integration with that nucleus.

Metropolitan Statistical Areas (MSAs): relatively freestanding Metropolitan Areas (MAs) not closely associated with other MAs. These areas typically are surrounded by non-metropolitan counties.

Minor civil divisions (MCDs): the primary political or administrative subdivisions of a county. MCDs represent many different kinds of legal entities with a wide variety of governmental and/or administrative functions. MCDs include, among others, American Indian reservations, assessment districts, boroughs, precincts, towns, and townships.

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P - R

Place: includes incorporated places (legally incorporated cityies, boroughs, towns, or villages) and census designated places (CDPs) (densely settled concentrations of population identifiable by name, but not legally incorporated).

Primary Metropolitan Statistical Areas (PMSA): large urbanized counties or clusters of counties that demonstrate very strong internal economic and social links, in addition to close ties to other portions of the larger area. When PMSAs are established, the larger area of which they are component parts is designated a Consolidated Metropolitan Statistical Area (CMSA).

Region: the Census divides the U.S. into four regions: Northeast, Midwest, South, West.

Rural: territory, population, and housing units not classified as urban.
In the 100% data products, "rural" is divided into:
In the sample data products, "rural" is subdivided into:
  • "Rural farm:" all rural households and housing units on farms (places from which $1,000 or more of agricultural products were sold in 1989).
  • "Rural nonfarm:" the remaining rural.

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S - T

State: the primary governmental divisions of the United States.

State [Indian] reservations: lands held in trust by State governments for the use and benefit of a given American Indian tribe. The names of American Indian reservations recognized by State governments, but not by the Federal Government, are followed by "[State]."

Tract: statistical subdivision of a Metropolitan Area or other densely populated county. Defined by local committees. Census tracts usually have between 2,500 and 8,000 persons. The spatial size of census tracts varies widely depending on the density of settlement.

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Unorganized territory: a county subdivision. In nine states (AR, IA, KS, LA, ME, MN, NC, ND, and SD), some counties contain territory that is not included in a minor civil division recognized by the Census Bureau. Each separate area of unorganized territory in these States is recognized as one or more separate county subdivisions for census purposes.

Urban: comprising all territory, population, and housing units in urbanized areas and in places of 2,500 or more persons outside urbanized areas.

Urban Fringe: densely settled territory adjacent to a central place. The urban fringe generally consists of contiguous territory having a density of least 1,000 persons per square mile.

Urban Places Outside Urbanized Areas: Incorporated places and Census-designated places of 2,500 or more outside urbanized areas.

Urbanized Area (UA): one or more places ("central place") and the adjacent densely settled surrounding territory ("urban fringe") that together have a minimum of 50,000 persons.

Urbanized Area Central Place: the dominant center(s) of an urbanized area.

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Page created on 11/15/99; last updated on 2/21/00.

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