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Data & Maps
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Resource Library
2021 Geographic Boundaries
Legal Areas
Legally defined geographic areas used in the ACS are updated on an annual basis from a variety of programs, including: the Boundary and Annexation Survey (BAS), the Redistricting Data Program and the School District Review Program.
Summary Level
|
Geographic Area |
Vintage of Geographic Area for 2021 ACS Estimate Year
|
|---|---|---|
040 |
State and State Equivalent |
January 1, 2021 |
050 |
County or equivalent (Alaska boroughs, Louisiana parishes, Puerto Rico municipios, independent cities) |
January 1, 2021 |
|
||
067 |
Township, Minor Civil Division (MCD)/Barrio and Barrio-Pueblo |
January 1, 2021 |
|
||
160 |
Incorporated Place |
January 1, 2021 |
|
||
230 |
Alaska Native Regional Corporations (ANRCs) |
2020 Census |
250/252/254 |
Federal American Indian Reservation (federal AIR) |
January 1, 2021 |
250/252 |
State American Indian Reservation (state AIR) |
2020 Census |
251 |
American Indian Tribal Subdivision, federal AIR |
January 1, 2021 |
250/254 |
Hawaiian Home Land (HHL) |
2020 Census |
|
||
500 |
Congressional District, Delegate District DC, Resident Commissioner District PR |
116th Congress of the United States/4 |
610/620 |
State Legislative Districts (Upper and Lower Chambers) |
2018 Legislative Session Year/4 |
950/960/970 |
School District (Elementary, Secondary, Unified) |
January 1, 2021 |
170 |
Consolidated City |
January 1, 2021 |
Statistical Areas
For statistical areas, boundary changes are mostly associated with updates from each decennial census. Statistical areas are designed to have stable boundaries over time.
Summary Level
|
Geographic Area |
Vintage of Geographic Area for 2021 ACS Estimate Year
|
|---|---|---|
050 |
County Equivalent (Census Areas in Alaska) |
January 1, 2021 |
|
||
060 |
Census County Division (CCD) |
2020 Census/1 |
Place |
||
160 |
Census Designated Place (CDP)/Zona Urbana and Comunidad |
2020 Census/1 |
|
||
250/252 |
Tribal Designated Statistical Area (TDSA) |
2020 Census |
250/252 |
State Designated Tribal Statistical Area (SDTSA) |
2020 Census |
250/252 |
Oklahoma Tribal Statistical Area (OTSA) |
2020 Census |
251 |
American Indian Tribal Subdivision (within OTSA) |
2020 Census |
256 |
Tribal Tract |
2020 Census/1 |
258 |
Tribal Block Group |
2020 Census/1 |
250/252 |
Alaska Native Village Statistical Area (ANVSA) |
2020 Census |
|
||
310 |
Metropolitan Statistical Area/Micropolitan Statistical Area |
March 6, 2020/3 |
312 |
Metropolitan Statistical Area/Micropolitan Statistical Area - Principal City |
|
350 |
New England City and Town Area (NECTA) |
March 6, 2020 |
352 |
New England City and Town Area - Principal City |
March 6, 2020/2 |
400 |
Urban Area |
2010 Census/4 |
140 |
Census Tract |
2020 Census/1 |
150 |
Census Block Group |
2020 Census/1 |
795 |
Public Use Microdata Area (PUMA) |
2010 Census/4 |
860 |
5-digit ZIP Code Tabulation Area (ZCTA) |
2020 Census
|
/1Changes to the boundaries of legal areas may cause complementary changes to the boundaries of selected statistical areas.
/2While the American Community Survey (ACS) data generally reflect the Office of Management and Budget (OMB) definitions of metropolitan and micropolitan statistical areas; in certain instances the names, codes, and boundaries of the principal cities shown in ACS tables may differ from the OMB definitions due to differences in the effective dates of the geographic entities.
/3The Census Bureau is planning on publishing the updated boundaries for this geographic summary level with the 2023 ACS release.
/4The Census Bureau is planning on publishing the updated boundaries for this geographic summary level with the 2022 ACS release.
Page Last Revised - August 23, 2023
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