Data sources and licences
Everything on the property pages is derived from public records. Currently loaded: 36,783 listings in 10 states, 30,840 with nomination summaries, 29,443 with photographs.
| Source | What we take from it | Licence | Refresh |
|---|---|---|---|
| NPS National Register database | Reference number, name, location, listing date, category, significance, NHL status, link to the archived file | US government work (public domain) | Monthly snapshot |
| NPS cultural-resource GIS (NRHP points and polygons) | Coordinates and district boundaries | US government work | Quarterly |
| National Archives Catalog, Record Group 79 | Nomination document PDFs and their OCR text (listings 1966–c.2012) | US government work | One-off backfill, then as scanned |
| Wikidata | Cross-reference IDs (Wikipedia article, Commons category), fallback coordinates | CC0 | Monthly |
| Wikimedia Commons | Photographs with author and licence | Per image: CC0, CC BY, CC BY-SA or public domain only. Credit shown under every photo. | Monthly |
| OpenStreetMap via Protomaps and Nominatim | Basemap tiles and address geocoding | ODbL | Tiles rebuilt quarterly |
Known gaps
- Nominations after about 2012 are held by the National Park Service, not the Archives, so recent listings usually have no summary.
- About 1% of listings have no published coordinates; some addresses are restricted by the NPS and shown as such.
- District membership is computed geometrically from NPS data and may differ from the nomination's list of contributing resources.
- Photos are matched through Wikidata; a wrong match is possible and can be reported.
Reuse
Our compilation (fields, coordinates, identifiers) is released under CC0 through the JSON API; machine summaries may be quoted with a link to the page. Photographs keep their original licences and must be credited as shown. Please do not scrape the HTML; use the API and llms.txt.