Boulderthon Half Marathon is expected to sell out. Over 4,000 runners are expected at this year’s Boulderthon from 50 states and 13 countries, with registrations coming in over 2x the rate of last year. 5k, 10k, Full Marathon are Nearing Capacity. Register today.
review of The Denver Post with Boulderthon startin line in the background

95% of runners would recommend to their friends, with #1 reason being Downtown Finish & Course Views.

Here are some of our favorite Boulderthon Race Reviews. Read more reviews here.

"Well Done. I’ve run nearly 50 marathons and/or half marathons and this ranks among the very best. Race day execution was flawless and I echo the previous comments about the professional staff and well organized volunteers groups. Looking forward to next year already!" - Brad

"Great Day, Great Race. I can’t imagine a marathon that is run any better. Everything went well, volunteers were plentiful and helpful, aid stations were great, and the weather was perfect for a long run. And Boulder turned out in force to cheer us on." - Matt

"This was my 1st half marathon race and I had a blast! Everyone was in a great mood and the course was beautiful! Thank you all!" - Jamie

"This was by far one of the best races I’ve participated in - Aid stations were dispersed well and there was so much help and encouragement from the volunteers and police officers. Thank you thank you thank you." - Miranda

"Fantastic Race. Great job to all who organized this event. You knocked it out of the park! From the great communications, well organized packet pick ups, friendly aid and water stations, and after party. It was so well run that you would never know it was the first one." - Saige D

"Fantastic First. Terrific race, beautiful course. Staff and volunteers were first class all the way!" - Pete

"Y’all pulled this off in good form. Great community organization and aid stations." - Ed

"Fun course, positive vibes, beautiful views and just enough support along the way. Thanks to all who helped make this race happen. I’ll be back every year. Perfect Race." - Jess