Jim Walmsley (born January 17, 1990) is an American long-distance runner. An ultra-trail specialist, his wins include the JFK 50 Mile in 2014, 2015 and 2016, the Lake Sonoma 50 in 2016 and 2018, the Tarawera Ultramarathon in 2017, and the Western States 100 in 2018, 2019, 2021, and 2024. In 2023, he became the first American man to win the Ultra-Trail du Mont-Blanc.

Walmsley has set 7 Fastest Known Time running records, including the speed record for the 44-mile Rim-to-Rim-to-Rim Grand Canyon crossing in 2016.

Sponsored by Hoka One One, Walmsley was named UltraRunner of the Year for four years in a row - 2016, 2017, 2018 and 2019. He also won UltraRunner of the Year in 2023 and 2025.

Walmsley qualified and ran in the 2020 Olympic trials in the marathon with his 2019 qualifying performance at the Houston half-marathon. While competing in the Hoka One One Project Carbon X 100K Challenge on May 5, 2019 he set a new world best for the 50 mile distance, completing it in 4:50:07 (besting Bruce Fordyce's previous 36-year old record by 14 seconds). Walmsley won the World Long Distance Mountain Running Championships in 2019.World Athletics: Walmsley and Simion take Long Course Titles at World Mountain Running Championships.

In 2023, Walmsley won Ultra Trail de Mont Blanc UTMB in a course record of 19:37:43 becoming the first American man to win the race.

Career High school Walmsley attended Horizon High School in Scottsdale, Arizona. In his senior year in 2007, he became Arizona's Division 5A-II cross country state champion, winning every race he ran in, and was named Runner of the Year. He finished 23rd in the national championships that year.

College He considered attending Arizona State, Georgetown, Iona College, Washington, California and the Air Force Academy, eventually choosing the latter. During his 4 years there, from 2008 to 2012, he ran cross country and also took part in the 5000 meters, 10,000 meters, and steeplechase. In 2012, as the captain of the cross country and long-distance running teams, his best times were 4:04 for the mile, 13:52 for 5000m, 29:08 for 10000m and 8:41 for the 3000m steeplechase.

Achievements 2014JFK 50 MileWashington County, Maryland, United States1st50 mile5 h 56 min 31 s2015JFK 50 MileWashington County, Maryland, United States1st50 mile5 h 47 min 37 s2016Bandera 100KBandera County, Texas, United States1st100 km7 h 46 min 37 s2016Moab Red Hot 55KMoab, Utah, United States1st55 km3 h 49 min 20 s2016Lake Sonoma 50Healdsburg, California, United States1st50 mile6 h 00 min 52 s2016JFK 50 MileWashington County, Maryland, United States1st50 mile5 h 21 min 29 s2017Tarawera UltramarathonNew Zealand1st100 km7 h 23 min 32 s2017Gorge Waterfalls 100KCascade Locks, Oregon, United States1st100 km8 h 20 min 28 s2017Kendall Mountain RunSilverton, Colorado, United States1st12 mile1 h 31 min 05 s2017Speedgoat 50KLittle Cottonwood Canyon, Utah, United States1st50 km5 h 04 min 55 s2017UTMBChamonix, France5th167 km20 h 11 min 38 s2018Lake Sonoma 50Healdsburg, California, United States1st50 mile5 h 51 min 16 s2018Western States 100Olympic Valley, California, United States1st100 mile14 h 30 min 04 s2019Houston half-marathonHouston, Texas, United States27thhalf-marathon1 h 04 min 00 s2019Hong Kong Fast 50 UltraHong Kong1st50 mile6 h 05 min 00 s2019Western States 100Olympic Valley, California, United States1st100 mile14 h 09 min 28 s2019UltravasanMora, Dalarna, Sweden1st90 km 5 h 47 min 28 s2020U.S. Olympic Marathon TrialsAtlanta, Georgia, United States22ndmarathon2 h 15 min 05 s2021Hoka One One Project Carbon XPhoenix, Arizona, United States1st100 km6 h 09 min 26 s2021Western States 100Olympic Valley, California, United States1st100 mile14 h 46 min 01 s2021 Ultra-trail Cape TownCape Town, South Africa1st100 km9 h 47 min 20 s2022UTMBChamonix, France4th167 km21 h 12 min 12 s2023UTMBChamonix, France1st172 km19 h 37 min 43 s2024Western States 100Olympic Valley, California, United States1st100 mile14 h 13 min 45 s2025Ultra Trail Chianti Castles (UTCC) by UTMBRadda in Chianti, Italy1st120 km9 h 59 min 48 s2025UTMB OCCChamonix, France1st61 km5 h 00 min 35 s2025World Mountain and Trail Running Championships - Long TrailCanfranc, Spain1st81.2 km8 h 35 min 11 s

Records + Course records set by Jim Walmsley Event Time Date JFK 50 5 h 21 min 28 s19 November 2016 Lake Sonoma 50 6 h 00 min 52 s9 April 2016 5 h 51 min 16 s — current record14 April 2018Bandera 100K 7 h 46 min 37 s — current record9 January 2016Tarawera Ultramarathon"Winners Smash Tarawera Ultra Records", Rotorua Daily Post, 11 Feb 2017. 7 h 23 min 32 s — current record11 February 2017Western States 100 14 h 30 min 04 s23 June 2018 14 h 09 min 28 s29 June 2019Ultra-Trail du Mont-Blanc19 h 37 min 43 s — current record2 September 2023

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