Sources and licences

Primary sources

All files were retrieved on 30 August 2026. The USGS imagery service is the one exception in this table: it is not downloaded and stored, it is requested by your browser when you scroll to a satellite view, so it has no retrieval date and no fixed vintage. Its contents can change without this site changing. Every other figure on this site comes from a file we downloaded on the date above and can reproduce.

Licence position, stated precisely

US Census Bureau data

Works prepared by officers or employees of the United States government as part of their official duties are not subject to domestic copyright protection under 17 U.S.C. 105. Census Bureau data files are therefore in the public domain and free to use, republish and build on.

Two real constraints remain, and this site observes both. Government material may not be used in a way that implies endorsement by a government agency, official or employee, and federal agency logos and seals may not be used without permission. This site does not display the Census Bureau seal and states plainly that it is not affiliated with, endorsed by, or certified by the Census Bureau.

We cite the Census Bureau as the source of the original data on every page that displays it. Where we compute something the Bureau does not publish, such as population density, the page says so and names both underlying products.

Wikidata

Structured data in Wikidata's main namespace is released under the Creative Commons CC0 1.0 Universal public domain dedication. There is no attribution requirement and no share-alike obligation. We credit it anyway, because a reader checking a county seat deserves to know where it came from and that it is community-maintained rather than official.

Because Wikidata is editable by anyone, we take a dated snapshot rather than querying it live. If a county seat here is wrong, that is our error to fix, not Wikidata's.

USGS National Map imagery

The National Map is produced by the US Geological Survey, a federal agency, and its imagery is in the public domain on the same statutory basis as the Census data above. The USGS asks that products using it carry an attribution, which the caption under every satellite view does.

We link the service rather than mirroring it. That is a deliberate trade: mirroring would mean storing tens of gigabytes of photographs and shipping stale ones, and the point of imagery is that it is current. The cost of the trade is that this is the only part of the site that depends on a server we do not control, and if that server is down the button says so instead of pretending. The boundary data, which is the part that matters, is ours and local.

Sources we deliberately do not use

OpenStreetMap, for tabular fields

OpenStreetMap data is licensed under the Open Database Licence, whose share-alike provision would attach to any derived database. Ingesting OSM attributes to fill in county seats would oblige us to publish this site's entire county dataset under the same terms. Wikidata provides the same coverage under CC0, so the trade is not worth making. We do not use OpenStreetMap basemap tiles either: this site renders vector boundaries directly and needs no tile server.

County Health Rankings and Roadmaps

Its terms of use grant access for personal or non-profit purposes and prohibit commercial use without prior written consent, explicitly including use for training commercial AI models. Excluded.

National Association of Counties, County Explorer

Published for non-commercial public use with mandatory attribution. Excluded.

Raw TIGER/Line shapefiles, for display

Public domain and entirely usable, but the polygons extend to the legal boundary out into territorial water. Rendered as a map, they fill in Chesapeake Bay and fuse Virginia's Eastern Shore to the mainland. We use the cartographic boundary files instead, which are pre-clipped to the shoreline. The full reasoning is in the methodology.

Congressional district

Not shipped at all. The Census Bureau's district-to-county crosswalk was last published in October 2024 and is stale for roughly ten states after the 2025 and 2026 mid-decade redistricting, and no replacement file exists. A wrong district on a county page is worse than no district, so the field is omitted until a federal source is current again.

Using our data

The processed data on this site is derived from public-domain federal sources and we place no additional restriction on it. Every state page offers its map as SVG, PNG and PDF, and every complete ranking table offers a CSV. Attribution to County Maps US is appreciated and not required; attribution to the US Census Bureau as the origin of the underlying figures is the part that actually matters.

If you need the boundary geometry in a GIS format, take it from the Census Bureau directly rather than from us. Ours is simplified for display and is not survey-accurate.Our download page says so on every file.