Run one of the fastest-growing, top-rated marathons in the country! After nearly tripling in size and selling out last year, Boulderthon has instituted a new 5,000 runner cap and is expected to sell out again this year.

Run a 5k, 10k, Half, or Full, at the foothills of the Rockies, in the stunning running mecca of Boulder. Run the streets Olympians train on, then celebrate at our epic after-party downtown!