We are thrilled to announce that Boulderthon™ remains scheduled for October 11th, 2020. We will continue to monitor & work closely with state & local officials on the latest covid-19 developments. We are in the process of assessing any and all modifications needed for runner and participant safety, including, but not limited to, staggered starts, course changes, & a new participant cap. In the event that we must postpone, all runners will have the option to defer their entry to either the next edition (Spring 2021), or the subsequent edition of the race (your choice), at no charge.


Running is the heartbeat of Boulder — one of the three hallmark recreational activities of our community (along with cycling and hiking, of course).

Together, we run the streets & trails of Boulder, and serve as one of the great training grounds for Olympians, world-class athletes, and leisure runners alike. We are so grateful & proud to have the world's best 10k — but despite running being hardwired into Boulder’s DNA — we have no signature city marathon.

This was the question we asked everyone — and we couldn’t find out why.

In one of the great health meccas of the US, rated one of the healthiest, happiest cities in the country, we couldn’t find a premier long-distance marathon.

After years in the making and the opportunity to acquire a 19-year-old race series, the Boulder Backroads Marathon & Half Marathon, we knew the time was now. As residents of Boulder County and local business owners, our goal from day 1 has been to create an inspiring, community-driven marathon series to serve as the premier fall race in the state. We decided to create the epic, downtown marathon race the beautiful city and community of Boulder deserves.

The Boulderthon™ was born.


Start at the beautiful Boulder Reservoir, and finish on Pearl St, Downtown, with sweeping views of the Flatirons throughout. Our Full and Half Marathon will run through County farmland before finishing in a first-of-its-kind, epic finish at the heart and soul of downtown Boulder.

Full Marathon - Strava RouteHalf Marathon - Strava Route

The Official Boulderthon Course Map will be released 5 months prior to Race Day, which will include a detailed overview of Medical & Aid Stations, Spectator Cheer Spots, Toilets, Starting & Finish Line Amenities, as well as our on-course Eldorado & Skratch Labs Hydration & Nutrition. Our Strava Routes may be adjusted based on higher-than-anticipated registration numbers to accommodate a larger participant count, and provide the best overall runner, spectator, and Boulder County & City of Boulder resident experience. If you have any immediate questions, feedback, or suggestions, please do not hesitate to contact us at hi@boulderthon.org.