Western States Endurance Run

Western States Endurance Run
Western States Endurance Run logo patch
DateLast weekend of June
LocationOlympic Valley, California
Auburn, California
Event typeUltramarathon trail run
Distance100.2 miles (161 km)
Established1977
Course recordsMen: 14:09:28 (2019)
Jim Walmsley
Women: 15:29:34 (2023)
Courtney Dauwalter
Official sitewww.wser.org
Runners, WS 2010.
The finish line to the Western States 100 at Placer High School

The Western States Endurance Run, known commonly as the Western States 100 or Western States, is a 100.2-mile (161 km) ultramarathon that takes place on California's Sierra Nevada Mountains trails each year on the last full weekend of June. Western States is one of the most competitive ultramarathons in the United States, and is administered by the nonprofit Western States Endurance Run Foundation.

The Western States 100 is one of the five 100-mile races that comprise the Grand Slam of Ultrarunning, which also includes the Old Dominion 100 in Virginia, the Vermont 100 Mile Endurance Run, the Wasatch Front 100 Mile Endurance Run in Utah, and the Leadville Trail 100 in Colorado. One of the more prestigious ultramarathons in the world, it is a qualifier for the UTMB World Series, although the UTMB organization has a major competing race in the same area with a similar course, called "Canyons Endurance Runs by UTMB".