Boundary Changes

Some areas of the nation may have reduced comparability, or non-comparability from one year to the next. Changes can happen for a variety of reasons including updates to tribal geography, annexation, legislative redistricting, geocoding updates, etc.

For those entities that experienced changes, making comparisons between an entity in its previous form to its current form should be done cautiously and with good understanding that the entity may be substantially different. TIGER Line Shapefile products are one tool used to perform detailed comparisons of the inventory and boundaries of geographic areas, by year. Information about these files and links to the mapping files themselves can be found at: TIGER Data Products Guide. Reference files for change can be located here: Relationship Files.

Core Based Statistical Areas

The 2023 ACS data products for Core Based Statistical Areas (CBSAs), also referred to as Metropolitan and Micropolitan Statistical Areas, are based on post-2020 Census revised delineations published by the Office of Management and Budget (OMB) on July 21, 2023 (OMB Bulletin No. 23-01). The revised delineations supersede the delineations published on March 6, 2020, and are based on official standards published in the Federal Register on July 16, 2021 (2020 Standards for Delineating Core Based Statistical Areas). For more information see: Metropolitan and Micropolitan.

Discontinuation of NECTAs Geography in ACS Products

Updates to the New England city and town areas (NECTAs), NECTA Divisions, PCI NECTAs, and Combined NECTAs have been discontinued in the 2023 ACS data products. For more information see: 2021-15159 [PDF] and the Federal Register Notice, 2020 Standards for Delineating Core Based Statistical Areas.