Are you ready for the Boulderthon? Join the fun and don’t get stuck in traffic this weekend.
The Boulderthon celebrates its 6th year this weekend. Read up on the race routes and road impacts.
Expect major traffic delays, significant pedestrian presence, and rolling road closures across Boulder and Boulder County during the upcoming Boulderthon race weekend, typically active from 7 a.m. to 4 p.m. on Sunday Sept. 27, 2026.
Boulderthon is a community nonprofit founded in 2021. In only its fifth year, the 2025 Boulderthon generated an estimated economic impact of $22.8 million in direct and indirect economic impact.
In just five years, Boulderthon has grown from 1,600 participants to more than 15,000 participants from around the globe.
