In its second annual edition, Boulderthon drew runners from all 50 states as well as 15 countries, as the signature marathon showcased the world-class city of Boulder set at the foothills of the spectacular Flatirons.

In 2023, Active named Boulderthon as one of the Top 5 Best Half Marathons in the United States.

“Racing in Boulder, Colorado, should be on every runner's bucket list, and the Boulderthon Half Marathon might be the perfect way to cross it off. The course starts at Boulder Reservoir, which gives you a true sense of Colorado's scenic beauty. Then you run along the foothills of the Flatirons. Finally, you wind your way into downtown Boulder and finish on the historic Pearl Street Mall. Veteran runners have touted this as one of the best race events of their lives; it has all the amenities of a big race (gear check, pace groups, plentiful aid stations) with the charm and attention to detail of a small race. Plus, it's a downhill finish!”