FILE PHOTO: Racers start the Colfax Marathon and Half Marathon on Saturday, Oct. 16, 2021 in Denver. (Michael Ciaglo/Special to The Denver Gazette)

Denver residents, watch out for runners on the streets this weekend.

More than 20,000 of them.

This weekend’s 17th Annual Denver Colfax Marathon stands as the biggest yet, according to organizers. It’s the first time the 26.2-mile race sold out. More than 20,000 runners are expected with “more marathon runners than ever before.”

It’s the only marathon in the world where runners pass through a working fire station, as they will Sunday morning at Denver Fire Department’s Station No. 1.

Here's what road closures to expect for the Colfax Marathon this weekend

“Year after year, we strive to make this race weekend better for runners,” said CEO Andrea Dowdy in a news release. “This might be one of the best marathon weekends to date and we are thrilled to welcome athletes to Denver’s favorite running weekend of the year.”

The event isn’t just a single day anymore — events are spread throughout the weekend starting Friday night with the Cigna Denver Colfax Marathon Expo at Empower Field at Mile High. It’s expected to draw 36,000 runners, families, friends and members of the public.

There’s a 5K run scheduled for Saturday morning at City Park. Sunday races include the marathon, marathon relays, half marathon and an “urban 10 miler.”

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Organizers welcomed new sponsors REI and Casa Bonita this year, to help with the charity organizations the marathon benefits.

“The Denver Colfax Marathon is a nonprofit that gives back to Colorado, so these companies help make our race a reality,” Dowdy said.

More than 150 nonprofits will participate in the Charity Partner Programs “using the marathon to raise money and awareness each year.”

Casa Bonita to sponsor the Denver Colfax Marathon's volunteer program

“Nonprofits get to keep all the money they raise through the marathon platform, and the marathon also awards $100,000 to local nonprofits every year,” organizers said.

The marathon starts at 6 a.m. Sunday. Expect traffic snarls and road closures between 6 a.m. and 1 p.m. along Colfax Avenue from Garrison Street west to Josephine Street east, and around City Park.

For more information, schedules, tickets or to volunteer visit

City Editor

Dennis Huspeni is a 30-year newspaper journalist who is the City Editor and covers metro Denver business.