Official State of Iowa Website

Boundary and Annexation Survey (BAS)

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.

Each year, all active, functioning legal government 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.
  • Consolidated cities.
  • Census designated places.

More Information

More information about the Boundary and Annexation Survey is on the Census Bureau's web site at