Angeles Crest 100 Mile Endurance Run

The Angeles Crest 100-Mile Endurance Run, or AC100, is an ultramarathon 100 miles (162 kilometers) long that takes place annually along trails through California's Angeles National Forest.

The course was originally designed to be a challenging 30-hour course, but due to its difficulty, the official cut-off time is set to 33 hours.

The race is limited to 150 participants; registrants must qualify by completing at least a 50-mile run in the previous year.

The race starts in Wrightwood, following portions of the Pacific Crest Trail (where it climbs Mount Baden-Powell), the Silver Moccasin Trail, and the Gabrielino Trail. It finishes at Loma Alta Park in Altadena, CA,near NASA's Jet Propulsion Laboratory.

The first event was held in 1986, and was mapped out by Del Beaudoin. Since then, the course has remained mostly consistent. The original finish line was the Rose Bowl in Pasadena through 1991. In 1992 the finish line was shifted to Johnson's Field in the Arroyo, adjacent to the Arroyo Seco. In 2008 the finish line was moved to Loma Alta Park, in Altadena.

Since the early 2000s the course has been extended an extra 1 mile around Cooper Canyon due to a closure enforced by the Forest Service to save the endangered Yellow-Legged Tree Frog.

The race was held in September until 2010, when the date as moved up August (except for 2011 and 2012, when it was held in July).

After the Station Fire cancelled the 2009 race, the race dates were changed in order to avoid the fire season.

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