Census Cartographic Boundary Files
The generalized boundary geometry the Census Bureau publishes for mapping, used to draw the shapes on the map.
The Census Bureau describes cartographic boundary files as "simplified representations of select geographic areas from the Census Bureau's Master Address File/Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) System", "specifically designed for small scale thematic mapping." They carry fewer vertices than the Bureau's detailed TIGER/Line equivalents, which is what makes a national map of every census tract practical to draw.
Coverage#
We use the 2025 vintage at 1:500,000 scale for both census tracts and places, covering the nation. The 2024 place boundaries are also held but are not what the map draws.
The Bureau reissues these files annually. Tract boundaries themselves are set at the decennial census and are of 2020 Census vintage; place boundaries are legal areas and can change between vintages as annexations and incorporations take effect.
How we use it#
This is the geometry behind the map — the outlines of the tracts and places you see and click. It carries shape only, no statistics, and produces no metric.
Considerations#
Because these boundaries are generalized, they are not suitable for precise geocoding, area or perimeter calculation, or determining which side of a line a specific address falls on. The Bureau states this in its own documentation. At close zoom a drawn boundary may sit slightly off the true legal line.
Boundary files are refreshed on the Bureau's annual schedule, so a very recent incorporation or annexation may not yet appear.
Citation#
U.S. Census Bureau, Cartographic Boundary Files, 1:500,000 scale, 2025 vintage.
Per Census Bureau citation policy, the Bureau is cited as the source of the original boundary files only.
References#
- 1Cartographic Boundary Fileshttps://www.census.gov/geographies/mapping-files/time-series/geo/cartographic-boundary.html
- 2Census Bureau citation policyhttps://www.census.gov/about/policies/citation.html