The Boundary and Annexation Survey (BAS) is the Census Bureau’s annual check-in with local government on where its legal boundaries actually are. Each year the Bureau contacts federally recognized American Indian areas, counties and county equivalents, incorporated places, and minor civil divisions, asking each to confirm that the Bureau has the correct boundary, name, and status for that government. The public and data users rely on the annual BAS boundaries as the official federal representation of boundaries for legal governments. The Census Bureau maintains this data in its MAF/TIGER System and publishes the results through the annual TIGER/Line release. For state and local officials, that makes BAS the ordinary, every-year channel through which an annexation or incorporation becomes part of the census geography on which later programs, including redistricting data products, are built. Below is a practical guide for getting started with your BAS submission.
Before logging into any Census Bureau tool to begin a BAS submission, local officials and GIS staff should gather a few specific items that the Census Bureau requires for every legal boundary change, since these cannot be entered after the fact. Legal boundary change submissions from incorporated places, minor civil divisions, and counties must include the legal documentation number (e.g., a law or ordinance number), the effective date, and the authorization type in the appropriate fields of the changes shapefile. (Census Bureau, BAS Technical Guide p8.) The authorization type field accepts one of five values: “ordinance,” “resolution,” “local law,” “state-level action,” or “other.” The effective date must reflect when the boundary change became legally operative, which may differ from the date the ordinance was passed or recorded. A shapefile or feature class showing the legal boundary of the government must also be prepared, with data formatted to agree with the Census Bureau’s naming convention for the same government as found in the NAME or NAMELSAD field. (Census Bureau BAS Partnership Toolbox Pro How-to Guide p.1) For tribal submissions, the actual legal documentation must accompany the change polygons; for all other submissions, it is requested but not required as long as the required data fields are complete.
Once changes are ready to submit, the delivery mechanism is SWIM for Partnership Toolbox users. GUPS Web submissions are submitted directly to the Census Bureau through the GUPS Web application itself, not through SWIM. The full step-by-step technical requirements, including shapefile naming conventions and field layouts, are documented in the BAS Technical Guide, which should be the first document any GIS staffer downloads before beginning the process. Below is the BAS schedule and a quick checklist:
Boundary Annexation Survey Annual Schedule
| January 1 | Legal boundary changes must be legally in effect on or before this date to be reported in the current survey year. |
|---|---|
| January to May | The Census Bureau conducts BAS. Eligible governments respond to BAS indicating if they have legal boundary, census-designated place (CDP), linear feature, or contact updates to report. Those with updates can choose to create their submission using the Census Bureau’s BAS Partnership Toolbox, Geographic Update Partnership Software Web (GUPS Web), or paper maps. |
| March 1 | Legal boundary changes returned by this date will be reflected in the American Community Survey and Population Estimates Program data and in next year’s BAS materials. |
| May 31 | Legal boundary changes returned by this date will be reflected in next year’s BAS materials. If time permits, boundary corrections returned by this date may also be reflected in next year’s BAS materials. |
BAS Pre-Submission Checklist
Administrative
- Locate your jurisdiction’s GOVID (formerly BASID). You can find it at the BAS Code Lists page
- Confirm your BAS contact is current. The Census Bureau sends SWIM tokens and outreach to the contact on file.
- Complete the Annual Response Form to notify the Census Bureau that you have changes to report.
Legal Documentation for Each Boundary Change
- Ordinance or resolution number (the legal document number authorizing the change)
- Authorization type: ordinance / resolution / local law / state-level action / other
- Effective date: the date the boundary change became legally operative
- Digital copy of the legal document (required for tribal submissions; strongly recommended for all others)
GIS / Shapefile
- Local boundary shapefile formatted to match Census naming conventions (NAME or NAMELSAD field)
- Census partnership shapefiles downloaded: edges, place, mcd/ccd, county, and water (auto-downloaded if using the BAS Partnership Toolbox)
- Review existing boundary in TIGERweb to identify any discrepancies before editing
Sources:
Census Bureau — BAS Technical Guide (PDF): census.gov/geo/pdfs/partnerships/bas/BAS_Technical_Guide.pdf
Census Bureau — BAS Partnership Toolbox Pro How-to Guide (PDF): census.gov/geo/pdfs/partnerships/bas/BAS_PartnershipToolboxPro_How-toGuide.pdf
Census Bureau — BAS Digital Respondent Guide (PDF): govinfo.gov/content/pkg/GOVPUB-C3-PURL-gpo106487/pdf
Census Bureau — BAS Code Lists / GOVID Lookup: census.gov/programs-surveys/bas/technical-documentation/code-lists.html
Census Bureau — BAS FAQ: census.gov/programs-surveys/bas/about/faq.html
Census Bureau — BAS Information for Respondents: census.gov/programs-surveys/bas/information.html
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