The ACS typically publishes estimates using the latest available geographic boundaries (also known as "vintages"). For ACS 5-year estimates, use the last year of the estimate period to determine the vintage. For example, the following datasets use the same vintages of geographic boundaries:

2022 ACS 1-year estimates
2018-2022 ACS 5-year estimates

To learn more about geographic concepts used in the ACS, check out our geographic handbook Geography and the American Community Survey: What Data Users Need to Know.

2009

Legal Areas
Statistical Areas

Legal Areas

The Census Bureau annually conducts the Boundary and Annexation Survey (BAS) to collect information about selected legally defined geographic areas. The ACS usually uses legal boundaries as of January 1 of the last year of the estimate period.

Geographic Area	2009 Estimate Year
State and State Equivalent	January 1, 2009
County or equivalent (Alaska boroughs, Louisiana parishes, Puerto Rico municipios, independent cities)	January 1, 2009
County Subdivision
Minor Civil Division (MCD)/Barrio and Barrio-Pueblo	January 1, 2009
Place
Incorporated Place	January 1, 2009
American Indian/Alaska Native/Hawaiian Home Land
Alaska Native Regional Corporations (ANRCs)	Census 2000
Federal American Indian Reservation (federal AIR)	January 1, 2009
State American Indian Reservation (state AIR)	Census 2000
American Indian Tribal Subdivision, federal AIR	January 1, 2009
Hawaiian Home Land (HHL)	Census 2000
Other Legal Areas
Congressional District, Delegate District DC, Resident Commissioner District PR	January 1, 2009¹
School District (Elementary, Secondary, Unified)^*	2007-2008 January 1, 2008
Consolidated City	January 1, 2009

^*School district boundaries are updated every two years as part of the School District Review Program.

¹113th Congress of the United States

Statistical Areas

For statistical areas, boundary changes most often take place with each decennial census. Statistical areas are designed to have stable boundaries.

Geographic Area	2009 Estimate Year
County Equivalent (Census Areas in Alaska)	January 1, 2009
County Subdivision
Census County Division (CCD)	Census 2000
Place
Census Designated Place (CDP)/Zona Urbana and Comunidad	Census 2000
American Indian/Alaska Native/Hawaiian Home Land
Tribal Designated Statistical Area (TDSA)	Census 2000
State Designated Tribal Statistical Area (SDTSA)	Census 2000
Oklahoma Tribal Statistical Area (OTSA)	Census 2000
American Indian Tribal Subdivision, OTSA	Census 2000
Tribal Tract	Not Included
Tribal Block Group	Not Included
Alaska Native Village Statistical Area (ANVSA)	Census 2000
Other Statistical Areas
Metropolitan Statistical Area/Micropolitan Statistical Area	November 2008
Metropolitan Statistical Area/Micropolitan Statistical Area - Principal City	November 2008*
New England City and Town Area (NECTA)	November 2008
New England City and Town Area - Principal city	November 2008*
Urban Area	Census 2000
Census Tract	Census 2000**
Census Block Group	Census 2000**
Public Use Microdata Area (PUMA)	Census 2000
5-digit ZIP Code Tabulation Area (ZCTA)	Not Included

*While 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.

**Census 2010 definitions were included in the 2005-2009 ACS estimates for tracts and block groups in select counties.