Boulderthon

Boulderthon is an American marathon non-profit organization in Boulder, Colorado, founded by Phil Dumontet.

Background
Boulderthon is the Boulder marathon and half-marathon. Phil Dumontet founded and acquired the race from Boulder Backroads in December 2019. 3,000 runners raced the Boulder Reservoir to Pearl Street on Sunday for the inaugural Boulderthon.

In 2023, Boulderthon was named one of the Best Fall Marathons in the US by Runners World.

The event nearly tripled in size in its second year, and added a kids fun run, a 5K, a 10K, as well as the signature full and half marathons. The race features an expo and fun finish line festivities, as well as runners from all 50 states, 15 countries, and an elite field.

In its third annual edition, Boulderthon become Colorado’s biggest fall race series, with an estimated 7,000+ runners total.

When the Twin Cities Marathon was cancelled due to heat, Boulderthon organizers opened their arms and honored all race bibs the following weekend, resulting in hundreds of Twin Cities participants running.

Dumontet spent four years to bring the event to life as he didn't want to put an extra strain on the town's race calendar, and acquiring a competition and bringing it downtown prevented that. To make the Boulderthon quintessentially Boulder, Dumontet focused on course development. The mostly flat, point-to-point route starts at Boulder Reservoir, finishes on the bricks of Pearl Street Mall, and includes striking views.