Denver Colfax Marathon 2027: Course, Elevation & Race Guide

The Denver Colfax Marathon 2027 takes place over the weekend of 14-16 May 2027, with the marathon itself on Sunday 16 May at 6:00 a.m. from City Park. It is Denver's only marathon, it runs the length of the longest continuous commercial street in America, and it remains the strangest big-city marathon in the country: you run through an NFL stadium, past a zoo, and get high-fives from firefighters standing inside their own fire station.

This guide covers the 2027 race specifically — the confirmed start times, the two Empower Field passes, the rerouted zoo mile — plus something the official site does not publish: a measured elevation profile of the whole course. The short version is that Colfax is not flat. It climbs about 360 feet from mile 5.5 to a high point near mile 15.5 in Lakewood, and the back half is largely downhill. Pacing it as though it were level is the most common way to have a bad day here.

Two trips through Empower Field. The organiser now bills the marathon as running through Empower Field at Mile High twice. It is the signature moment of the race either way — the tunnel, the warning track, the empty bowl — and getting it twice is the sort of thing runners plan a season around.

A new zoo mile. The half marathon is the only race in the United States besides Baltimore's that runs through a zoo, and for 2027 that mile is being redrawn now that construction on the Denver Zoo's Down Under exhibit has finished.

Registration opened early. Entries for 2027 went on sale on 18 August 2026, with the first 500 registrations saving roughly $75. Colfax prices in tiers, so the practical advice is unchanged: register early or pay for it.

The 2027 course map had not been published when this guide was written. The flyover below shows the 2026 alignment, which the out-and-back on Colfax has held for years — but confirm the official map at runcolfax.org before race week, particularly around the stadium.

Colfax is usually described as flat. It is not. Sampled every half mile along the course, the profile shows a low of 5,180 feet and a high of 5,541 feet — a spread of 361 feet — with the top of the course at roughly mile 15.5.

Those are terrain heights from a public elevation model rather than a surveyed course profile, so treat the exact figures as indicative and the organiser's published ascent as authoritative. The shape, though, is unambiguous, and it is the useful part: a net climb of about 360 feet from mile 5.5 to mile 15.5, then a long descent home.

Two practical consequences. First, an even-effort run produces a slower first half and a faster second half — which means the splits that feel like failure at halfway are usually the right ones. Second, the descent from mile 16 to mile 21 does real damage to quads. Runners who train downhill running finish this course; runners who only train climbs do not.

Race it in three parts: hold back through the fast opening five miles, work the climb from the stadium to Lakewood, then run the downhill with your feet under you rather than out in front. The Urban 10 Miler course is literally the last ten miles of this — which is why locals use it as the fast-finish preview.

The half marathon is the one with the zoo mile — rerouted for 2027 — and the fire station run-through, and it takes in VooDoo Doughnut, the Cathedral Basilica, the Capitol, Civic Center Park, the 16th Street Mall and the Convention Center on the way back to City Park. Aid stations run every two miles with gels around mile 8.

The Urban 10 Miler runs the final ten miles of the marathon course: the Empower Field run-through, downtown, Confluence and Cherry Creek, then 17th Avenue to City Park. It starts in waves from RMCAD and filters runners into the ongoing marathon, so you finish alongside people who have been out there since six.

The marathon relay splits 26.2 miles across five legs and is where the weekend's charity money is: teams compete for $175,000 in awards designated to charity partners, and the race distributes about $150,000 to charities each year. There are Open, Corporate, Government and Public School Teacher divisions.

The Colfax 5K is the Saturday race, wrapping City Park and Ferril Lake with downtown and the mountains in view. It has a stroller-friendly wave and a dog wave, and it is the only race of the weekend with race-morning packet pickup.

Mid-May in Denver is genuinely unpredictable — this is a city that has had snow in the same week as 85°F — so rather than quote a seasonal average we pulled the hourly reanalysis temperature at City Park for 16 May in each of the eleven years from 2015 to 2025.

The 6 a.m. gun is cold. The eleven-year mean was 46°F, with a coldest year at 39°F and a warmest at 52°F. That is throwaway-layer weather, and the early start is a gift rather than an inconvenience.

It warms about 19°F by 11 a.m. A four-hour marathoner finishes into an average of 61°F; a five-hour marathoner into 65°F, and in the warmest of those eleven years it was 73°F. The back half of this course is exposed, so the later you finish the more the sun matters.

Rain is a real but minority risk. Six of the eleven years recorded no precipitation at all on 16 May, and the eleven-year mean was 0.09 inches — skewed by 2016's half-inch. The more reliable annoyance is wind: peak gusts on those mornings averaged around 12 mph, noticeably breezier than Boulder in September.

City Park sits at almost exactly 5,280 feet, and the course spends the middle third of the race higher than that. Air here holds roughly 17% less oxygen than at sea level. For a visiting runner that is worth two to five percent on marathon pace — minutes, not seconds.

The counterintuitive part is the arrival window. Either come in within 24 hours of the gun and race before your body reacts, or come at least two weeks out and let it adapt. Landing three days before is the worst of both.

14-16 May 2027

🗺️ Downtown Denver to the City Park start line

1. 1. Allow an hour more than you think you need
   For a 6:00 a.m. gun, be moving by 4:45 a.m. Colfax closes early and the streets around City Park go first.
2. 2. Driving: park east or north of City Park, not on Colfax
   The neighbourhoods off 17th and 23rd Avenues stay open longest. Do not plan to cross the course by car after 5:30 a.m.
3. 3. Rideshare: drop at 17th and York, then walk in
   Drop-offs closer than that get caught behind closures. It is a five-minute walk to the Ferril Lake start.
4. 4. Staying downtown? Walk or take a short ride to City Park
   It is roughly two miles from Union Station — walkable as a warm-up if you are running the 5K, less appealing before a marathon.
5. 5. Coming from the airport: RTD's A Line to Union Station
   About 37 minutes to downtown, then a short ride east. Worth doing the day before rather than on race morning.

They are near-mirror images. Colfax front-loads its downhill and hides its climb in the middle; Boulderthon front-loads its downhill and hides its climb at the end. Colfax is urban, loud and full of set-pieces; Boulderthon is quieter and prettier. Our full Boulderthon 2026 course guide has the same treatment for that race, and the Colfax guide hub covers every distance in this weekend. If you are planning the trip around more than the race, see what else is on in Denver that weekend.

Running Colfax in 2027?

Registration is open for all eight races on the weekend, and Colfax prices in tiers — entering early is the cheapest it will be.

Get Denver race updates

Course changes, race-week weather and the best spectator corners for every big Front Range race, from 303Happenings.

Last verified September 2026 by the 303Happenings desk. Hours, prices, and access change — confirm current details with the venue.