Angeles Forest 100K
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Angeles Forest 100K
The Angeles Forest 100K and Red Box Mountain Marathon take place on March 20, 2027, at Loma Alta Park in Altadena, CA. The event is the first annual running of these mountain races and is independent of the Angeles Crest 100 Mile Endurance Run.
Routes cross the San Gabriel Mountains and include steep, technical singletrack, long descents, and sections that are remote and far from road access. The 100K covers roughly sixty-two miles of mountain terrain and was designed to be completed in one day. The marathon follows steep, rocky trails in the same front range.
Distances:
- 100K - 62 miles through the San Gabriel Mountains
- Red Box Mountain Marathon - mountain marathon on steep, rocky trail
Participation requirements and logistics noted by the organizers include a trail work obligation for 100K runners: complete eight hours of organized trail work between October 4, 2026 and March 13, 2027. A $100 trail donation option will be available in lieu of trail work, and funds will go to local trail restoration. Marathon runners are not required to complete trail work.
The event has a weather, safety and modification policy. In extreme conditions race management may modify routes, change aid locations or cutoff times, postpone or cancel the event, or move entries to an alternate date with one-time deferral options. Registrations include published entry fees and may be subject to change. Visit the organization's website for the most recent information.
