Very limited space remains in the 5K, Half Marathon and Kids Run
BOULDER, Colo. – Boulderthon powered by lululemon has announced that its marathon and 10K have officially sold out for the 2026 event, marking another major milestone for one of the fastest-growing running events in the country.
Only very limited space remains in the 5K, half marathon and Kids Run, with the distances quickly approaching capacity.
Founded in 2021 as a nonprofit community running event with 1,600 runners, Boulderthon has grown to more than 17,000 runners in 2026, attracting runners from across Colorado, throughout the United States and around the world. What began as a new hometown race has evolved into one of Colorado’s premier running weekends, bringing together thousands of runners, spectators, volunteers, local businesses and community partners while showcasing Boulder and Boulder County.
“Selling out several distances and nearing capacity across the entire event is an incredible milestone for Boulderthon and for our community,” said Phil Dumontet, Founder of Boulderthon. “When we launched Boulderthon in 2021, our vision was to create a world-class running experience rooted in Boulder. The growth we’ve seen since then has been extraordinary, and it is a reflection of the runners, volunteers, partners and community members who continue to believe in this event.”
The 2026 Boulderthon will feature a marathon, half marathon, 10K, 5K and the Boulder Country Day School Kids Run, creating a race-weekend experience for runners of all ages and abilities.
As a nonprofit event, Boulderthon’s impact extends well beyond race weekend. Through its partnership with the PLAY Boulder Foundation, Boulderthon is contributing $50,000 to help resurface the parking lot at Tom Watson Park, install a new water fountain and improve the park’s grounds and landscaping. Boulderthon has also pledged to match every dollar donated by the community through Dec. 31, up to an additional $50,000, bringing its total potential commitment to the park to $100,000.
For more information on Boulderthon, powered by lululemon, visit www.boulderthon.org, and follow the event on Facebook and Instagram.
ABOUT BOULDERTHON POWERED BY LULULEMON
Boulderthon powered by lululemon is a 501(c)(3) community nonprofit founded in 2021 by Phil Dumontet to bring a world-class marathon to Boulder. In only its fifth year, the event generated an estimated economic impact of $13.9 million locally and regionally. The race has grown from 1,600 participants to more than 15,000 participants, making it one of the fastest-growing races in the U.S. The event was recently recognized by USA Today as one of the Top 10 races in the U.S. Outside of race weekend, the organization leads ongoing volunteer and environmental adoption efforts, hosts free year-round community events, and has a program to promote accessibility to racing through no-cost bibs. The race offers a full marathon, half marathon, 10K, 5K and Kids Run. The marathon is a Boston Marathon Qualifier and a USATF Sanctioned Event, measured by a Level A USATF Course Measurer. For more information, visit www.boulderthon.org.