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Legal Boundary Change/Annexation Data

The Boundary and Annexation Survey (BAS) annexation data are composed of attribute information for legal boundary changes, which state, county, and local governments reported to the BAS and the BAS State Certification Program.  Legal boundary changes are changes to county, incorporated place, and minor civil division boundaries resulting from a legal action such as an annexation or deannexation/detachment.  The annexation data do not include boundary corrections that were not implemented by a legal action.

Legal Boundary Change Files for Active Incorporated Places

BAS Year(s) Effective Date Census Available Format(s) File Description
2022 January 1, 2022   Excel, TXT TXT
2021 January 1, 2021   Excel, TXT TXT
January 1, 2020
  Excel, TXT TXT
2019 January 1, 2019   Excel, TXT TXT
2018 January 1, 2018   Excel, TXT TXT
2017 January 1, 2017   Excel, TXT TXT
2016 January 1, 2016   Excel, TXT TXT
2015 January 1, 2015   Excel, TXT TXT
2014 January 1, 2014   Excel, TXT TXT
2013 January 1, 2013   Excel, TXT TXT
2012 January 1, 2012   Excel, TXT TXT
2011 January 1, 2011   Excel, TXT TXT
2001-2010 January 1, 2010 2010 Excel, TXT TXT
1991-2000 January 1, 2000 2000 Excel, TXT TXT
1981-1990 January 1, 1990 1990 PDF TXT
1971-1980 January 1, 1980 1980 PDF TXT

DISCLAIMER: The U.S. Census Bureau makes no claims to the completeness of the annexation data in the boundary change files. The data in these files were collected through the BAS and BAS State Certification program in which state, county, and local governments voluntarily participated. The level of completeness and accuracy of the data are subject to the participants’ continued effort in providing the Census Bureau with up to date boundary information. In addition, the BAS Year in the table above does not necessarily correspond to the year in which the boundary change went into effect. By policy, the Census Bureau will accept legal boundary changes from BAS participants as long as these changes were in effect as of January 1 of the active BAS year. For example, during the 2010 BAS, the Census Bureau accepted legal boundary changes from previous years up to January 1, 2010. When researching boundary changes effective from a particular year, be sure to search multiple BAS year ranges since governments may report effective boundary changes during a later BAS year. Also, be advised that information collected prior to the 2011 BAS is archival; several boundary change records in these files may no longer be in effect or may be superseded by later boundary change actions. The Census Bureau deemed the boundary changes to be in effect during the time of collection and during tabulation for the decennial census. Please read the file descriptions before downloading the data files.

Related Information

Page Last Revised - December 12, 2022
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