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Colfax Marathon: Starting Times, Routes and Road Closures

Colfax Marathon weekend — and the road closures and chaos that come with it — is upon us.
Image: Runners take off under a banner reading "Colfax Marathon"
A melee of runners take off in a previous Colfax Marathon Colfax Marathon
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Colfax Avenue, at nearly 50 miles in length stretching across the Denver metro from Golden to Strasburg, is famous for being one of the longest continuous commercial streets in the United States and infamous for being the most wicked street in the country.

It's also the namesake of the Colfax Marathon, Denver's only legit 26.2-mile foot race.

Colfax Marathon weekend is upon us, with the 5k on Saturday, May 17, and the marathon, half marathon, urban ten-miler, and marathon relay will occur on Sunday, May 18. Whether you're a registered runner, an aspirant who hasn't registered, an observer hoping to cheer on the athletes or a local just trying to avoid road closures, here's what you need to know.


When and Where Are the Races?

The Colfax 5k begins Saturday morning at 9 a.m. in City Park. This is the only race that allows runners to bring their dogs along.

The Colfax Marathon Relay kicks off at 6 a.m. on Sunday in City Park, and features five relay legs along the marathon route stretching west into Lakewood to Garrison Street.

The main event, the Colfax Marathon, also begins at 6 a.m. Sunday in City Park, on the east side of Ferrill Lake.

The Colfax Half Marathon will start at 6:30 a.m. in City Park, on the east side of Ferrill Lake. It's on a new route that will take runners around the City Park Golf Course, but still includes the Denver Zoo mile, where spectators come in an array of species.

The Urban 10 Miler has a staggered start between 7:45 a.m. and 8:45 a.m., and covers the final ten miles of the marathon, starting at Rocky Mountain College of Art and Design at 1600 Pierce Street in Lakewood.


Can I Still Register for the Colfax Marathon?

You can still register for the marathon, the Urban 10 Miler, and the 5k at the Colfax Marathon Expo at Empower Field at Mile High Stadium on Friday, May 16, between 1 and 7 p.m., or Saturday, May 17, from 10 a.m. to 5 p.m.

All runners except those in the 5k must attend the expo to pick up their bibs before the Sunday races.


Where Can I Watch From?

Spectators can track runners via the website to find where their favorite is, mile by mile.

Prime viewing locations for the marathon, marathon relay, and Urban 10 Miler are 14th and Larimer streets, Sports Authority Field at Mile High, Sloan's Lake, Rocky Mountain College of Art and Design, and Dudley Street and West Colfax Avenue.


Colfax Marathon Road Closures

Road closures will be between 5 a.m. and 1 p.m. on Sunday, with rolling closures and reopenings after the last runner goes by. For north/south travelers, I-25 will remain open, along with Kipling Street to the west, and all roads east of Colorado Boulevard will be open.

If you're traveling east or west, stay south of Colfax from 14th Avenue on —  or if you're north of Colfax, take 30th Avenue or above.

Use the map below as your guide, and avoid the areas in pink to stay out of marathon-related traffic jams.
click to enlarge A street map showing road closures and the race routes for the 2025 Colfax Marathon
Avoid the areas in pink to stay out of marathon traffic. I-25 will remain open.
runcolfax.org