Boundary Annexation Survey (BAS)

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The U.S. Census Bureau conducts the Boundary and Annexation Survey (BAS) annually to collect information about selected legally defined geographic areas. The BAS is used to update information about the legal boundaries and names of all governments.

In 2015 OFM and the U.S. Census Bureau (USCB) entered into an agreement solidifying OFM’s role as the approving authority for city boundary changes with the USCB.  Since that time OFM has been coordinating a consolidated BAS response for all counties and cities in the state. This benefits local governments making changes to city limits if they follow state laws and procedures. OFM will submit all boundary changes which are processed and approved through our normal process to the census bureau. Cities no longer need to report boundary change information to the census bureau.  OFM reports these changes to the Census bureau quarterly based on revenue distribution quarters.

That said, historical discrepancies in city limits abound, we would like cities to review their boundaries by comparing their boundaries to information on the census BAS website. The more eyes the better. If differences are found please report the issue to us.  Jurisdictions may 1) prepare change polygons following the directions described on the Census BAS webpage and send that information to OFM or 2) prepare a map showing the discrepancy and send it to OFM. In most cases we will need to the ordinance or BLA number(s) of area associated with the issue. 

In cases where an annexation or BLA was never reported to OFM jurisdictions will still need to fulfill all of the normal annexation requirements before OFM can approve the change. Once approved OFM will include the change in the next quarterly submission to the census bureau.

Please read the BAS respondent guidelines and email us at if you plan to formally review your city's boundaries and submit changes to OFM. We must receive change polygons or maps by February 14 to meet the March 1 submission deadline or by May 15 to meet the May 31 submission deadline. It is important to note that we at OFM are bound by the BAS guidelines like everyone else and there are some changes that are not accepted through the BAS program. We don’t want you spending a lot of time on changes that cannot be used. Please contact us if you have questions.

It is important to know that the OFM\Census MOU does not cover all of the possible geographic boundary changes the BAS program accepts.  OFM’s obligation is for city limits.  We do not have the information for example to support re-alignment of streets or changes or to make changes to address ranges. If local governments see the need to make such changes in their jurisdictions information and they follow the BAS reporting rules described on the Census website we can still help.  OFM will either submit the properly prepared files for the jurisdiction or facilitation the submission of the changes with the USCB by requesting a SWIM token.


Last updated
Tuesday, June 27, 2023
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