Boulder, Colorado, United States
The Boulderthon Marathon draws approximately 1,500 finishers each September on an urban and foothills road in Boulder, United States. Its branding and local support turned it into a fast-growing Rocky Mountain marathon almost immediately. The course passes Pearl Street, CU Boulder, and open roads beneath the Flatirons with broad Front Range views. Pearl Street, CU Boulder, and open roads beneath the Flatirons climb with broad Front Range views on this fast-growing Rocky Mountain marathon.
Boulderthon Marathon is a certified 42.195 km (26.2 mile) marathon — the standard World Athletics marathon distance.
The next Boulderthon Marathon is scheduled for Sunday, 6 September 2026 with a 7:00 am start. The certified course covers 42.195 km (26.2 miles) with 150 m of climbing on a rolling with moderate climbs layout.
Starts and finishes near downtown Boulder and the civic park area. The course passes Pearl Street, CU Boulder, and open roads beneath the Flatirons with broad Front Range views. Foothill rollers demand patience before the flats return, and Pearl Street crowds swell as leaders reach the civic park finish.
The Boulderthon Marathon course is rolling with moderate climbs over 42.195 km (26.2 miles). Runners cover 150 metres of climbing and 140 metres of descent, with a net climb of 10 metres from start to finish.
The Boulderthon Marathon uses open online registration at boulderthon.org with no ballot or qualifying time required. Sign-up for the September race typically opens the previous year and places are allocated first-come, first-served. Tiered pricing increases closer to race day, and charity bibs are available through partner organisations when general entry closes.
Last updated 18 July 2026. Edition dates and course details are reviewed regularly.
Other races closest to Boulder.
The Denver Colfax Marathon attracts approximately 2,178 finishers each May along America's longest continuous main street — Colfax Avenue. The course follows the full 42 km of Colfax from the eastern plains through downtown Denver to the western foothills at 1,600 m altitude. May's Mile High City spring and the iconic Colfax Avenue strip make it one of Colorado's most distinctive urban marathons.
Next race: Sunday, 23 May 2027
The Colorado Marathon draws approximately 1,800 finishers each May on a canyon point-to-point road in Fort Collins, United States. It delivers a scenic mountain-canyon descent without the extreme grade of some western downhill marathons. The course follows the Cache la Poudre River, red-rock canyon walls, and the approach into northern Colorado neighborhoods. The route is net downhill overall.
Next race: Sunday, 2 May 2027
The Utah Valley Marathon draws approximately 2,200 finishers each June on a canyon point-to-point road in Provo, United States. Its long gentle descent makes it a common target for personal bests and Boston qualifying attempts. The route passes Deer Creek-adjacent canyon roads, the Provo River corridor, and broad urban streets near BYU. The route is net downhill overall.
Next race: Sunday, 6 June 2027
The REVEL Big Cottonwood Marathon is a net-downhill speed course drawing approximately 2,500 finishers each September through Utah's Wasatch Mountains. Starting at Brighton Ski Resort (2,590 m) and descending Big Cottonwood Canyon to Salt Lake City, the course drops roughly 1,200 m on scenic mountain highway. September's crisp alpine morning and the fast descent make it one of America's most popular personal-best marathons.
Next race: Saturday, 19 September 2026
The Salt Lake City Marathon draws approximately 1,500 finishers each April on an urban road in Salt Lake City, United States. Descending from the east bench gives the race a quick first half before the city grid settles the pace. The course passes This Is The Place Heritage Park, Liberty Park, and temple district streets with Wasatch views throughout. The route is net downhill overall.
Next race: Sunday, 4 April 2027
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