A single factual statement inside an entry, held separately from the prose around it, so that clicking it shows the exact source that carries it and any caveat attached to it.
🤖 This definition was generated with AI from the sources linked throughout. It has not had a complete human review — treat it as a starting point and follow the sources. How this works.
A claim is one factual statement, held as its own object rather than dissolved into the paragraph around it. Each has a stable identifier, the sources that carry it, a note on what those sources actually say, and — where one applies — a caveat naming what the claim cannot settle.
On the page this is what the dotted underlines are. Turn on Sources in the text and each marked passage opens a card showing the source behind that specific sentence, so you never have to guess which of the entry's sources supports which half of it. Without JavaScript the same marks are ordinary links into the bibliography.
The wording is held to the letter: the stored claim text must appear verbatim in the published entry, and the site refuses to build if an edit moves the sentence without moving the claim with it. That is what stops an approval from quietly going stale after a later rewrite.
Coverage varies by entry. San Francisco's automated water meters and Boston's CharlieCard are annotated close to sentence by sentence; many entries carry a smaller set covering their impact figures. Where a claim has been read and signed off by a person, the card says who and when — otherwise it says plainly that it has not yet been individually verified.
Added 2026-08-25 · Part of the growing Smart City Glossary