Boulderthon Sells Out Marathon Distance Entries for 2025 Event

August 12, 2025

The 5th edition of the city signature marathon will host 3,100 participants along the new 26.2-mile course

BOULDER, Colo. (August 12, 2025) /ENDURANCE SPORTSWIRE/ — Boulderthon, presented by PUMA, has announced the sell out of its marathon distance ahead of the 2025 event, taking place Sept. 28. These runners will be taking part in the brand new marathon route that features a net elevation gain cut by about 40%, going from 982 feet to 603 feet.

The event is seeing record numbers across the board, with the total field expected to once again surpass previous years with an estimated 15,000 participants joining race day. Other distances are also close to their sell-out numbers.

“Seeing the growth of Boulderthon year-after-year has been unimaginable,” said Alexa Squillaro, event director of Boulderthon, presented by PUMA. “It’s been amazing helping build this event into what it is today, and I can’t thank the Boulderthon team enough for all their hard work that is paying off in tremendous ways. Boulderthon has already made its mark among U.S. races, and we’re just getting started!”

Boulderthon, presented by Puma, offers five distances for participants to take part in, the marathon, half marathon, 10K, 5K and Kids Run. The 10K course will run participants through the streets of Boulder, showcasing the scenic town, before leading them to Downtown Boulder for the iconic finish on the historic Pearl Street Mall. The second annual Heart to Heart 5K by BCH features an all-road, fast and flat experience for all participants, allowing wheelchair athletes and those utilizing wheeled vehicles, like duo runners, to take part in the event.

The top-rated, fast-growing multi-distance event became the second-largest race in Colorado in its first year of existence, and the largest fall running event in the state. Last year, Boulderthon drew nearly 10,000 runners from all 50 states as well as 22 countries. This secured its entry into the list of the top 100 largest running events in the country, as reported by RunSignUp. In 2023, Active.com named Boulderthon one of the Top 5 Best Half Marathons in the United States, and the following year the 5K and half marathon courses were both named a top 10 in their categories by USA Today’s 10Best Readers’ Choice awards.

For more information on Boulderthon, presented by PUMA, visit www.boulderthon.org, and follow the event on Facebook and Instagram.

ABOUT BOULDERTHON® PRESENTED BY PUMA

Boulderthon, presented by PUMA, was created in 2021 by avid New York Road Runner, Phil Dumontet, with the goal of bringing a world-class marathon to one of the great running hubs of the country. It is a Boston Marathon Qualifying (BQ), USATF Sanctioned Event, measured by a Level A USATF Course Measurer, representing the highest level of certification for a marathon race. The race offers a full marathon, half marathon, 10K, 5K and children’s races. For more information, visit www.boulderthon.org.