Cartographic Boundary Files Select a page from one of the following menus... Boundary Files... Alaska Native Regional Corporations American Indian Areas/Alaska Native Areas/Hawaiian Home Lands American Indian Tribal Subdivisions Census Block Groups Census Divisions Census Regions Census Tracts Congressional Districts Consolidated Cities County & County Equivalent Areas County Subdivisions Incorporated Places/Census Designated Places Metropolitan Areas New England County Metropolitan Areas Oregon Urban Growth Areas Public Use Microdata Areas School Districts State & State Equivalent Areas State Legislative Districts - Lower/House State Legislative Districts - Upper/Senate Subbarrios (Puerto Rico only) Traffic Analysis Zones Tribal Block Groups Tribal Census Tracts Urbanized Areas Voting Districts ZIP Code Tabulation Areas (ZCTAs) Descriptions and Metadata... Alaska Native Regional Corporations American Indian Areas/Alaska Native Areas/Hawaiian Home Lands American Indian Tribal Subdivisions Census Block Groups Census Divisions Census Regions Census Tracts Congressional Districts Consolidated Cities County & County Equivalent Areas County Subdivisions Incorporated Places/Census Designated Places Metropolitan Areas New England County Metropolitan Areas Oregon Urban Growth Areas Public Use Microdata Areas School Districts State & State Equivalent Areas State Legislative Districts - Lower/House State Legislative Districts - Upper/Senate Subbarrios (Puerto Rico only) Traffic Analysis Zones Tribal Block Groups Tribal Census Tracts Urbanized Areas Voting Districts ZIP Code Tabulation Areas (ZCTAs) Technical Information... ASCII File Information Filenaming Conventions Projection Information Scale, Generalization, and Limitations Site Information... Site Map Site News Related Sites and Resources... American FactFinder Census Bureau Home Geographic Services & Information Geography Division Map Gallery Geographic Areas Reference Manual State and County QuickFacts TIGER U.S. Gazetteer LandView FIPS Information USGS Utilities

Census Block Group Cartographic Boundary File Descriptions and Metadata Geographic Area Description | Metadata Titles 2000 Census Block Groups   1990 Census Block Groups Geographic Area Description A block group (BG) is a cluster of census blocks having the same first digit of their four-digit identifying numbers within a census tract. For example, block group 3 (BG 3) within a census tract includes all blocks numbered from 3000 to 3999. BGs generally contain between 600 and 3,000 people, with an optimum size of 1,500 people. Most BGs were delineated by local participants as part of the U.S. Census Bureau's Participant Statistical Areas Program. The U.S. Census Bureau delineated BGs only where a local, state, or tribal government declined to participate or where the U.S. Census Bureau could not identify a potential local or tribal participant. BGs never cross the boundaries of states, counties, or statistically equivalent entities, except for a BG delineated by American Indian tribal authorities, and then only when tabulated within the American Indian hierarchy. BGs never cross the boundaries of census tracts, but may cross the boundary of any other geographic entity required as a census block boundary (see "CENSUS BLOCK"). In decennial census data tabulations, a BG may be split to present data for every unique combination of American Indian area, Alaska Native area, Hawaiian home land, congressional district, county subdivision, place, voting district, or other tabulation entity shown in the data products. For example, if BG 3 is partly in a city and partly outside the city, there are separate tabulated records for each portion of BG 3. BGs are used in tabulating data nationwide, as was done for the 1990 census, for all block-numbered areas in the 1980 census, and for selected areas in the 1970 census. For purposes of data presentation, BGs are a substitute for the enumeration districts (EDs) used for reporting data in many parts of the United States for the 1970 and 1980 censuses and in all areas before 1970. Return to Top | Geographic Area Description | Metadata Metadata 2000 BGs | 1990 BGs Title 2000 Census Block Groups Location http://www.census.gov/geo/www/cob/bg2000.html Geography Each State, D.C., Puerto Rico Vintage January 1, 2000 Formats ARC/INFO Export (.e00), Arcview Shapefile, and ARC/INFO Ungenerate (ASCII) Projection Geographic (Lat/Lon) Datum NAD83 Distributor Department of Commerce, Census Bureau, Geography Division Originator Department of Commerce, Census Bureau, Geography Division For further information on the Cartographic Boundary Files click HERE. Title 1990 Block Groups Location http://www.census.gov/geo/www/cob/bg1990.html Geography Each State, D.C., American Samoa, Guam, N. Marianas Islands, Palau, Puerto Rico, Virgin Islands Vintage January 1, 1990 Formats ARC/INFO Export (.e00), Arcview Shapefile, and ARC/INFO Ungenerate (ASCII) Projection Geographic (Lat/Lon) Datum NAD27 Distributor Department of Commerce, Census Bureau, Geography Division Originator Department of Commerce, Census Bureau, Geography Division For further information on the Cartographic Boundary Files click HERE. Return to Top | Geographic Area Description | Metadata

Last Revised: May 18 2001 · geography@geo.census.gov· Geography Division · US Census Bureau · (301) 457-1128
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