The Boundary and Annexation Survey (BAS) provides tribal, state, and local governments an opportunity to review the Census Bureau’s legal boundary data to ensure the Census Bureau has the correct boundary, name, and status information. BAS also allows participants to review and provide updates to census designated places. Maintaining correct boundaries helps ensure that the Census Bureau assigns the appropriate housing and population counts to each government. Title 13, Section 6, United States Code authorizes this survey.

Each year, all active, functioning legal governments are surveyed. This includes almost 40,000 governments across the United States and its territories. These governments can update boundaries and features for:

• Federally recognized tribes with a reservation or off-reservation trust land.
• States.
• Counties or county equivalents, such as boroughs or parishes.
• Minor civil divisions, such as towns and townships.
• Incorporated places, such as cities, towns, and villages.
• Consolidated cities.
• Census designated places.

The federal government allocates more than $2.3 trillion in federal funds annually for health, welfare, infrastructure, education, and other federal programs and services. Maintaining correct boundaries helps ensure that the Census Bureau assigns the appropriate housing and population counts to each government so that governments receive funds appropriately and have the best data available for decision-making.

The Census Bureau uses the boundaries collected in BAS to tabulate data for various censuses and surveys including the decennial census, American Community Survey, and Population Estimates Program. It also uses the legal boundaries collected through BAS to support several other programs such as Congressional and State Legislative redistricting, the Economic Census, the Geographic Update Population Certification Program, and the Special Census program. For additional information, see the BAS Methodology webpage.

For information on how the Census Bureau collects and maintains American Indian Areas, see the American Indian and Alaska Native Programs webpage.