About the atlas
What this is.
A field atlas of American hundred-milers — every race mapped, dated, and rated by the people who finished them.
The atlas
Hundred Atlas covers the hundred-mile-ish distance — roughly 95 to 105 miles — across the United States. Around 255 races are indexed: their dates, terrain, course type, qualifier status, and, where runners have submitted them, six-dimension finisher ratings. The goal is a single, trustworthy reference for the US hundred-mile calendar, not a media property.
Where the data comes from
Each entry is compiled from public sources: the race's own website, registration pages (UltraSignup, RunSignup, and similar), and results archives. We cross-reference multiple sources before publishing a date. Elevation and terrain data come from USGS 3DEP and Mapzen/AWS Open Data. Nothing here is generated or estimated from a model — every record was touched by a human.
Confirmed vs. projected dates
A date marked with a tilde (~) is projected— the race has not yet formally announced its date for the year. We carry the projection so the atlas stays usable for planning; always verify with the race before booking travel or requesting race-day leave. A clean date with no qualifier is confirmed from the race organizer or registration page.
Corrections and additions
Data goes stale. Races move dates, change courses, or go on hiatus. If something is wrong, email [email protected] with the race name and what's off — we'll fix it. If a hundred-miler is missing entirely, submit it here.
Lineage
Built in the spirit of run100s.com's old race directory — the thing that used to exist and quietly kept everyone organized. That resource is gone; this one is an attempt to fill the gap without the cruft.