Denver Colfax Marathon

DenverColoradoUnited States

Next race

Sunday, 23 May 2027

6:00 am start

Distance

42.195 km / 26.2 mi

Urban road

Elevation

Rolling · 100 m gain

100 m climbing

Race profile

Overview

The Denver Colfax Marathon attracts approximately 2,178 finishers each May along America's longest continuous main street — Colfax Avenue. The course follows the full 42 km of Colfax from the eastern plains through downtown Denver to the western foothills at 1,600 m altitude. May's Mile High City spring and the iconic Colfax Avenue strip make it one of Colorado's most distinctive urban marathons.

Denver Colfax Marathon is a certified 42.195 km (26.2 mile) marathon — the standard World Athletics marathon distance.

Typical participants: Approximately 2,178 finishers

Weather: Mild spring
11–17°C · humidity 50–70%
Marathon weather guide →

Course & terrain

Denver Colfax Marathon course

Route map and elevation profile for race-week planning.

The Denver Colfax Marathon is a point-to-point tour of the full length of Colfax Avenue from Aurora through downtown Denver toward the western finish near Golden or the State Capitol. The avenue itself stays mostly level, but racing at roughly 1,600 m altitude and across Denver's long urban straights makes the second half the tougher mental and physical test. Spectators gather at the start in Aurora, along key Colfax neighbourhoods, and at the city-centre finish festival.

Denver Colfax Marathon route map

Registration

Denver Colfax Marathon entry requirements

For the Denver Colfax Marathon, the Colfax Marathon is held in May, typically on the fourth Sunday. Registration is at https://www.runcolfax.org/.

Common questions

Frequently Asked Questions

Is the Denver Colfax Marathon a Boston Qualifier?: The Denver Colfax Marathon is a Boston Qualifier. The Denver Colfax Marathon holds a certified 42.195 km course that can be used for Boston Marathon qualifying times, subject to current Boston Athletic Association standards and the race's USATF (or equivalent) certification status in the registration year.
What is the Denver Colfax Marathon elevation profile?: The Denver Colfax Marathon has 100 metres of total climbing and 95 metres of descent over 42.195 km (26.2 miles). The course is rolling, with 5 metres of net climb from start to finish.
Where can I find the Denver Colfax Marathon route map?: This page includes a Denver Colfax Marathon course map showing the full 42.195 km route from start to finish. The point-to-point route follows the entire length of Colfax Avenue through downtown Denver.
How long is the Denver Colfax Marathon?: The Denver Colfax Marathon is the standard marathon distance of 42.195 kilometres (26.2 miles), certified to World Athletics rules. From the eastern end of Colfax Avenue in Aurora to the western end near Golden or the Colorado State Capitol.
What time does the Denver Colfax Marathon start?: The 2027 Denver Colfax Marathon starts at 6:00 am local time on Sunday, 23 May 2027. Arrive early for baggage drop and corral access — official race communications confirm any last-minute schedule changes.
What is Colfax Avenue?: Colfax Avenue is the longest continuous main street in America, stretching 42+ miles through the Denver metro. The marathon follows its length through the Mile High City.
When is the Denver Colfax Marathon?: The Colfax Marathon is held in May, typically on the fourth Sunday.
How does Denver's altitude affect the Colfax Marathon?: Denver sits at 1,600 m (5,280 ft). The flat Colfax course belies the thin-air challenge — pace conservatively and hydrate well.
Where does the Colfax Marathon start and finish?: The race starts at the eastern end of Colfax in Aurora and finishes at the western end near Golden or the State Capitol area.
What weather should I expect in Denver in May?: May in Denver is unpredictable spring weather, often 8–20 °C (46–68 °F) with possible afternoon thunderstorms. Layers and sun protection are both important.

Last updated 11 October 2026. Edition dates and course details are reviewed regularly.

Close to this race

Nearby Marathons

Other races closest to Denver.

BoulderColoradoUnited States· 39 km away

Boulderthon Marathon

The Boulderthon Marathon draws approximately 1,500 finishers each September on an urban and foothills road in Boulder, United States. Its branding and local support turned it into a fast-growing Rocky Mountain marathon almost immediately. The course passes Pearl Street, CU Boulder, and open roads beneath the Flatirons with broad Front Range views. Rolling terrain with moderate climbs shapes the middle miles.

Next race: Sunday, 26 September 2027

Fort CollinsColoradoUnited States· 94 km away

Colorado Marathon

The Colorado Marathon draws approximately 1,800 finishers each May on a canyon point-to-point road in Fort Collins, United States. It delivers a scenic mountain-canyon descent without the extreme grade of some western downhill marathons. The course follows the Cache la Poudre River, red-rock canyon walls, and the approach into northern Colorado neighborhoods. The route is net downhill overall.

Next race: Sunday, 2 May 2027

LaramieWyomingUnited States· 182 km away

Med Bow Rail Marathon

The Med Bow Rail Marathon draws approximately 45 finishers each May on a scenic trail road in Laramie, United States. Laramie's Med Bow Rail Marathon uses a rail-trail corridor through southeastern Wyoming's high country. The course follows the Medicine Bow Rail Trail through high-plains and mountain-foothill scenery. Rolling terrain with moderate climbs shapes the middle miles.

Next race: Sunday, 2 May 2027

CasperWyomingUnited States· 365 km away

Casper Marathon

The Casper Marathon draws approximately 89 finishers each June on a scenic road in Casper, United States. Wyoming's fast-growing Casper Marathon is a USATF-certified Boston qualifier in the heart of the state. The course follows Casper river trails, prairie roads, and wide-open Wyoming vistas. Gentle undulations are the only breaks on an otherwise flat profile.

Next race: Sunday, 6 June 2027

Green RiverWyomingUnited States· 427 km away

Run with the Horses Marathon

The Run with the Horses Marathon draws approximately 57 finishers each August on a scenic road in Green River, United States. Green River's Run with the Horses Marathon serves southwestern Wyoming on a rolling high-desert course. The course tours Green River neighborhoods and high-desert plateau roads. Rolling terrain with moderate climbs shapes the middle miles.

Next race: Sunday, 1 August 2027

DeadwoodSouth DakotaUnited States· 526 km away

Deadwood-Mickelson Trail Marathon

The Deadwood-Mickelson Trail Marathon draws approximately 238 finishers each June on a scenic trail road in Deadwood, United States. South Dakota's largest running event by participation finishes in the historic landmark town of Deadwood. The course follows the crushed-limestone Mickelson Trail through Black Hills forests, creeks, and mining-country scenery. Expect significant climbs on this hilly course.

Next race: Sunday, 6 June 2027

Find a Marathon →

Planning guides

Related guides

Practical guides to help you plan, train for, and run this race.

Best Boston Qualifier Marathons 2026

Best Boston Qualifier Marathons 2026

Which US marathons produce Boston qualifiers in practice — course data, typical BQ rates, and how to match a race to your qualifying window.

Marathon Course Profiles Explained

Marathon Course Profiles Explained

What flat, rolling, and hilly really mean — and how to read elevation gain, net change, and altitude on a marathon course.

Marathon Weather: What to Expect

Marathon Weather: What to Expect

How temperature, humidity, wind, and rain affect marathon performance — and how to use typical race-day weather when choosing a start line.

View all marathon guides →