Boulderthon: Boulder Marathon

Race facts

• The course covers 21.1 km.
• It takes place on a Sunday, September 27, 2026 — autumn in this part of the world.
• The closest comparable running event is Estes Epic Ultra Run & MTB Race in Estes Park, 45 km away, on September 26, 2026.
• 12 of the 12 most similar events take place in the same month.