Colfax Marathon, Half Marathon, Relay & Urban 10-Miler

Saturday, October 16, 2021 • Denver, CO • Course Map

Note: A new course is in progress for 2021. The below course description details the previous course.

Several thousand runners and walkers take the streets of Denver and nearby Aurora each spring for the Kaiser Permanente Colfax Marathon, Half Marathon, Relay & Urban 10-Miler, which marks its 15th annual running this year and features a half marathon route that runs through the Denver Zoo.

Like the full marathon, the event’s 13.1-mile race features a long, straight out-and-back course that starts and finishes at Denver’s City Park and takes runners along two long parallel straightaway runs from the park to the turnaround and back, including some steady elevation climbs (and descents).

From the starting line at Denver City Park, a 330-acre urban park located in the east-central part of the city and home to both the Denver Zoo and the city’s Museum of Nature and Science, the race takes runners around City Park Lake, past Duck Lake and out onto 17th in the first mile of the race.

Next it brings runners back into the park and then again out onto 23rd Avenue, from which they’ll head into the 80-acre Denver Zoo, and run along the paved trails and roads past many of the animal exhibits.

Between miles 3 and 4, they’ll run past the Denver Museum of Nature and Science, and then head out into the city on Montview Boulevard. This stretch will feature a long, flat straightaway through residential streets, many blocks with tree-shaded, sidewalks and plenty of locals out cheering you on.

There’s a gradual climb in the first half of the race followed by a gradual descent later on in the second half, after runners make the turnaround in Aurora. Runners finish the race just a stone’s throw from where they started, as the last mile or so of the race takes the field from 17th back into the park.

As they’re heading back toward the heart of Denver through Aurora along 17th, runners also can enjoy the city skyline, marked by the downtown skyscrapers as well as Invesco Field, home of the NFL’s Denver Broncos.

More than 5,800 runners crossed the finish line in the half marathon alone in 2014, and walkers are welcome as long as you can keep a pace of 18 minutes per mile or faster.

Race Weather & Climate

Located along the front range of the Rocky Mountains in northern central Colorado, Denver typically experiences warmer but often still cool weather conditions in the early fall, with cold mornings a possibility.

On race day (Oct. 16), the average low is 43ºF and the average high is 64ºF.

Past Results

Course Map

See the race route map for the Colfax Half Marathon here.

Starting Time

see race website

Course Time Limit

  • 4 hours – half marathon
  • 6 hours – full marathon
  • 2.5 hours – Urban 10-miler


see race website


To reserve your spot in the 2021 running of Denver’s Kaiser Permanente Colfax Marathon, Half Marathon, Marathon Relay or 10-mile race, register online at the event website here.

Official Race Website


Ever run in the Colfax Half Marathon? Share your impressions here, or post your review in the Comments below.

See more races in: October, Colorado

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