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Ruth Anderson Memorial Endurance Run

Lakeshore, United States • 11 Oct 2025

Ruth Anderson Memorial Endurance Run is an annual multi-distance ultramarathon staged in San Francisco, California. Runners compete on a 4.475-mile paved bike-path loop around Lake Merced, with dirt shoulders and one aid station per loop. Each participant can pursue the event’s standard distances — roughly 31.1 miles (50K), 44.5 miles (50M), or 100K — with course cutoffs at about 7.5 and 11 hours to complete longer distances. Elevation changes total significant climbs and descents per loop (roughly 2,488' climb and 2,555' descent per circuit). The race has a long history since 1986, with USATF-certified course maps and detailed finishers’ data available online. Visit the organization's website for the most recent information.

United States California Lakeshore

Race information

Website
100 km
100k
50 mi
50 Miles
50 km
50k
Visit the organization's website for the most recent information.
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