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BAS Methodology

The Boundary and Annexation Survey (BAS) fulfills the agency’s responsibility as part of the National Spatial Data Infrastructure, for which the Office of Management and Budget (OMB) Circular A–16 designates the Census Bureau as the lead federal agency for maintaining national data about legal government boundaries, as well as statistical and administrative boundaries. BAS supports the spatial data steward responsibilities of the OMB E-Gov, Data.gov, the National Map, the Geographic Names Information System, the Federal Geographic Data Committee, and the Geospatial One-Stop. Title 13, Section 6, United States Code authorizes this survey.

View the OMB Federal Register Notice for BAS

BAS Results

The Census Bureau provides the results of BAS to the public as part of the agency’s annual release of TIGER/Line products and via the TIGERweb online mapping application. The public and data users rely on the annual BAS boundaries as the official federal representation of boundaries for legal governments.

Numerous federal programs rely on accurate boundaries from each BAS, including:

  • The U.S. Geological Survey depicts the annual BAS boundaries on the National Map online.
  • The Department of Housing and Urban Development uses BAS boundaries to determine jurisdictional eligibility for various grant programs, such as the Community Development Block Grant program.
  • The Department of Agriculture uses BAS boundaries to determine eligibility for various rural housing and economic development programs.

The Census Bureau uses BAS results to support several programs, including:

  • Congressional and State Legislative redistricting,
  • The decennial census and related preparatory tests,
  • The Economic Census, and
  • The Special Census Program.

In addition, the American Community Survey uses BAS boundaries to tabulate survey results, and the Population Estimates Program uses BAS to ensure that the most current boundaries are available in the annual release of population estimates.



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