Half marathon
9.27.26
THE HALF MARATHON WORTH RUNNING
Boulderthon was named among the Best Fall Marathons by Runners World, as well as the best Half Marathon in Colorado and one of the Top 13 Most Beautiful Half Marathons in the World by HalfMarathons.net.
Boulderthon has doubled every year since its inception. In its fifth annual edition, Boulderthon drew over 15,000 runners from all 50 states as well as 22 countries, as the signature marathon showcased the world-class city of Boulder set at the foothills of the spectacular Flatirons.
Join us for the largest September running weekend in the U.S. on Sunday, September 27th, 2026 for the sixth annual Boulderthon Marathon in stunning Boulder, Colorado.
Boulderthon Half Marathon
Date: Sunday, September 27th 2026
Start Time: 7:00am
BOULDERTHON HALF MARATHON REGISTRATION
Registration for the Boulderthon Half Marathon is now open.
