Boundary and Annexation Survey (BAS)

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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.

What is BAS?

How to Get Started

BAS Videos

Response Info

BAS Questionnaires

Access the BAS Annual Response/Contact Update form here.

BAS State Agreements

The purpose of a BAS state agreement is to coordinate information sharing between state governments and the Census Bureau.

Consolidated BAS (CBAS) Agreements

The Census Bureau offers Consolidated BAS agreements to counties interested in submitting boundary changes for the legal governments within their jurisdiction.

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Reviewing Tools

Reference Map | 2021

2021 BAS Maps

The 2021 BAS Maps display legal boundaries and names effective as of January 1, 2020.

Mapping File

2021 BAS Partnership Shapefiles

Download the Census Bureau's 2021 BAS partnership shapefiles to map your boundaries.

BAS Partnership Tools

BAS partnership tools to help BAS participants.

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Response Methods

Here are the different methods to respond to the BAS.

Training Events

BAS Webinars

The U.S. Census Bureau will offer informational Boundary and Annexation Survey (BAS) webinars in early 2021.

Boundary and Annexation Survey (BAS)

Boundary and Annexation Survey (BAS)

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