Tennessee BAS Program page
Tennessee program email: cities@cot.tn.gov
Census Bureau Program web page
Census email contact: rdo@census.gov
What is BAS?
The Boundary and Annexation Survey (BAS) is an annual process conducted by the Census Bureau to collect information about the legal boundaries of counties and incorporated areas. The annual changes include those boundaries that are in effect on January 1 of each year. For the 2030 Census, the boundaries shown in both data and geographic products will reflect a community’s limits on January 1, 2030.
In Tennessee, the Comptroller of the Treasury coordinates the collection of boundary changes each year, submitting a single response to the BAS for the entire state.
A special decennial Census operation called the Boundary Validation Program (BVP) provides a final opportunity for the highest elected official in each community to review their jurisdiction’s boundaries prior to the 2030 Census tabulation. It runs concurrently with the 2030 BAS review.
Why does BAS matter to a community?
Ensuring that the Census Bureau has both current and accurate corporate limits is a critical part of obtaining a complete census count. If boundaries are incorrect, some of a community’s population will be reported as being resident in another municipality or the unincorporated part of the county. This can adversely affect funding, the accuracy of other statistics and complicates redistricting.
A census challenge can correct erroneous boundaries shown in the 2030 Census, but the process is time-consuming, the outcome is not guaranteed, and the Bureau’s other decennial census products are not updated to reflect changes if the challenge succeeds.
How does BAS work?
Tennessee statutes require municipalities to report annexations and deannexations to the Comptroller of the Treasury. The state compiles these changes each year and submits them to the Census Bureau on behalf of all Tennessee counties and municipalities. For those changes to be reflected in the current year’s census products, the following schedule applies to the State of Tennessee’s consolidated submission:
Early January
The Census Bureau sends out notifications and instructions for the annual BAS cycle
January 1st
Legal boundary changes must be in effect by this date to be included in the current year’s data.
March 1st
First BAS deadline; the state’s boundary changes submitted by this date will be reflected in the current year’s American Community Survey and Population Estimates Program data.
May 31st
The state’s final deadline for submitting boundary changes for inclusion in the following year’s BAS materials.
Note that the Comptroller may establish other deadlines in order to meet the Bureau’s timeline. Tennessee is one of fifteen states with a consolidated BAS agreement where local governments report annexations and other boundary changes to a state agency. Communities can contact the comptroller to submit new materials or to obtain assistance reviewing their boundary.
Who can participate in the BAS?
The highest-elected official in each county or municipality may receive an annual BAS notice from the Census Bureau, however it will include instructions to contact the Comptroller to review the boundary or submit annexation-related changes. The terms of the consolidated BAS agreement preclude the communities from participating directly with the Census Bureau.
All questions and/or documents regarding the program should be submitted to through cities@cot.tn.gov.
What software and data are required?
The Census Bureau boundaries for every county and municipality in Tennessee can be reviewed in one of three ways:
- TIGERWEB – An online mapping tool which can be used to view the boundaries of incorporated places (municipalities)
- BAS Maps – Detailed PDF maps showing the current corporate limits for each municipality
- BAS Shapefiles – GIS data files which can be downloaded
- Communities can contact the Comptroller’s office for assistance with the review, to submit annexations or to discuss discrepancies identified on the Census Bureau site.