Sep
28
Sunday

Run Boulderthon: The Boulder Marathon

Website

The Run Boulderthon: The Boulder Marathon will take place in Boulder on Sunday 28 September 2025. You can run between 5 and 42 kilometers. Visit the organization's website for the most recent information.

United States Colorado Boulder
Always double-check with the organizer's website – things can change, and we might have sprinted past a few details!
42 km
Marathon
21 km
Half Marathon
10 km
10k
5 km
Kids Run

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23
Saturday

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Saturday

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23
Saturday

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5 km
Aug
24
Sunday

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8 km
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