Boulderthon Debuts New Course Routes Ahead of 5th Edition

July 8, 2025

The new Marathon and Half Marathon courses feature over 40% reduction in elevation gain and take runners through the scenic Boulder County backroads used for Olympic training

BOULDER, Colo. (July 8, 2025) /ENDURANCE SPORTSWIRE/  — Boulderthon, presented by PUMA, has announced new courses for the 2025 running event taking place on Sept. 28. Both the marathon and half marathon routes will take participants on new journeys to some of Boulder’s most popular and highly regarded training routes. All distances will still feature the historic start and finish line located on Pearl Street Mall in Downtown Boulder. Those interested in experiencing the new courses are encouraged to register soon, as the full marathon is already 95% sold out and other events are filling quickly.

Boulderthon’s half marathon course will take participants through different landscapes, with stunning views of the Flatirons along the way. The marathon will expand from the half marathon course, taking participants on North 51st Street past the Boulder Reservoir and along Boulder County backroads frequently used by training Olympians, before looping to return for the famous Pearl Street Mall finish. Both the 13.1-mile and 26.2-mile distances have also cut overall elevation gain. The marathon net elevation gain will be cut by about 40%, going from 982 feet to 603 feet, and the half marathon elevation gain will be cut by almost 50%, going from 384 feet to 203 feet.

“The new course was designed with both the runner’s experience in mind, and the opportunity to showcase the one-of-a-kind running trails found only here in the Boulder area,” said Alexa Squillaro, event director of Boulderthon, presented by PUMA. “These new routes will give participants an even more enjoyable experience, down to the ease of the paths to the unique sightseeing throughout the whole journey. Boulder is a terrific place to explore, and with this new route, we strongly believe Boulderthon will solidify itself as a true destination race.”

The new course was designed in partnership with Boulderthon’s head coach, Nell Rojas, and Boulderthon’s city and county partners. Rojas is an American marathon runner with top American finishes at both the 2021 and 2022 Boston Marathon, a top 10 finish at the 2022 New York City Marathon and 2020 Olympic Marathon Trials and notable success in claiming a 10-mile US Championship title and victory at Grandma’s Marathon. Beyond her own athletic pursuits, Nell champions inclusivity within the running community, advocating for people of color and promoting women’s empowerment. With over 20 years of coaching experience, Nell also dedicates herself to coaching athletes of all abilities to achieve their own running goals.

“Its been so amazing working with our local city and county partners on designing a course that will highlight even more of the beauty within Boulder County,” said Nell Rojas, head coach at Boulderthon, presented by PUMA. “We put a lot of thought into these routes, and feel great about their debut!”

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.