Editorial and machine-generated content policy

Two kinds of text

Guides are written by a person, carry a byline and a last-updated date, cite named sources and are revised when the rules change. Property summaries are generated by a language model from the official nomination document and are labelled as such on every page, with this notice:

This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail.

How summaries are produced

The nomination form is retrieved from the National Archives catalog (OCR text of the scanned PDF). Nominations the Archives has not scanned, including most listings after 2012, have no summary.
The model is instructed to use only facts stated in the document, to return "not stated" rather than guess, to ignore form boilerplate, and never to mention current owners or occupants even when the form names them.
The output is a fixed set of fields (what it is, why it was listed, period, architect or builder, style, criteria, status if stated) plus a 120–180 word narrative and a confidence rating. Every page shows the model, prompt version and generation date so a reader can judge the vintage.
Summaries are regenerated when the prompt improves; the prompt version is stored with each summary.

What we never publish

Names of current private owners or occupants, assessor data, sale prices or anything beyond the address the National Park Service itself publishes. Where the NPS restricts an address, we do too.
Text copied from Wikipedia or any other site. Wikipedia is used to cross-check facts and is linked, not reproduced.
Photographs without a free licence and a credit.

Indexing

A property page is submitted to search engines only when it has a nomination summary, or at least a photo and coordinates. Thin pages exist for completeness and are marked noindex until they earn it.

Corrections

Report an error with the page URL and the NRHP reference number by email to the address on the About page. Confirmed errors are fixed in the database (not just the page) and the summary is regenerated or hand-edited; hand edits are marked as such.

Independence

National Historical Register is not affiliated with the National Park Service, the Department of the Interior or any State Historic Preservation Office, and accepts no payment to list, remove or alter a property page. Commercial relationships (referrals, affiliates) are labelled where they appear.