Boundary and Annexation Survey (BAS)
Boundary and Annexation Survey (BAS)
The U.S. Census Bureau conducts the Boundary and Annexation Survey (BAS) annually to collect information about selected legally defined geographic areas. BAS is used to update information about the legal boundaries and names of all governments.
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Respond to BASComplete the Boundary and Annexation Survey (BAS) Annual Response Form.
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BAS Participation and ResponseMaps showing Boundary and Annexation Survey (BAS) participation and response information.
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BAS VideosThis collection of videos provides an overview of the Boundary and Annexation Survey (BAS) and information needed to get started with a program submission.
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Response MethodsMethods for creating a submission and reporting updates to the Boundary and Annexation Survey (BAS).
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BAS ScheduleImportant dates to know for the Boundary and Annexation Survey (BAS).
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Respondent How-To GuidesHow-to guides for the different response methods for the Boundary and Annexation Survey (BAS).
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Reference Map2026 BAS MapsThe 2026 BAS maps display legal boundaries and names as reported through the 2025 BAS.
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Mapping FilePartnership ShapefilesView the available shapefiles that allow us to share data with and capture data from our partners.
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Data ToolTIGERwebTIGERweb and TIGERweb Decennial web-based applications allow visualization of TIGER (Topologically Integrated Geographic Encoding and Referencing) data.
BAS Agreements
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Page Last Revised - August 18, 2026