The Denver Colfax Marathon returns on Sunday, May 17, 2026 for its 21st edition. The race spans 26.2 miles along one of America's most iconic streets, taking runners from City Park through downtown Denver, past Empower Field at Mile High, along Sloan's Lake with Rocky Mountain views, and deep into the western neighborhoods of Lakewood before returning to a hero's finish at Ferril Lake.
With five race distances — Marathon, Half Marathon, 10 Miler, 5K, and Marathon Relay — there's an event for every fitness level. This guide covers everything you need: the full course map, mile-by-mile breakdown, elevation profile, aid stations, spectator tips, and race-day logistics.
Course Overview
The Denver Colfax Marathon is an out-and-back course centered on East Colfax Avenue, the longest commercial street in America. The route starts and finishes at Ferril Lake in City Park, taking runners on a tour of Denver's most vibrant neighborhoods.
The course is USATF certified and qualifies for Boston Marathon entry. It's run almost entirely on city streets that are closed to traffic. The mix of flat urban stretches and gentle rolling terrain makes it a great PR course — many runners call it one of the best urban marathons in the country.
Altitude Advisory: At 5,280 feet, oxygen levels are about 17% lower than at sea level. If traveling from lower elevations, arrive 2–3 days early to acclimatize. Drink 50% more water than normal and start conservatively. Many runners negative-split this course by holding back in the first half.
Mile-by-Mile Route Breakdown
Elevation Profile & Terrain
The course ranges from approximately 5,180 to 5,480 feet in elevation, with a total ascent of roughly 700 feet. It's considered moderately flat by marathon standards.
The main elevation gain occurs between miles 6–13 as the route climbs gradually westward. The return trip is a gentle net downhill. The biggest challenge isn't the hills — it's the altitude. Plan to run 1–3 minutes per mile slower than your sea-level pace, and prioritize hydration.
Altitude Training Tips
- Arrive 2–3 days early to begin acclimatizing
- Increase water intake by 50% starting 3 days before
- Start 30–60 seconds per mile slower than goal pace
- Avoid alcohol for 48 hours before the race
- Use electrolyte supplements at every other aid station
- Practice breathing techniques for thin air (nose breathing)
Race Day Logistics
Best Spectator Spots
- Empower Field at Mile High (Mile 7)The most electric spot on the course. Arrive early to grab a spot near the stadium tunnel entrance.
- Sloan’s Lake (Mile 8.5)Wide-open sightlines with mountain views. Drummers and dragon boat crews create an unforgettable atmosphere.
- Colorado State Capitol (Mile 2.5 & 24.5)See runners twice — once heading out and once coming home. Great for signs and cowbells.
- City Park Finish (Mile 26.2)Stake out a spot along the final 400 meters at Ferril Lake for the most emotional moments.
- 17th Avenue (Mile 3.5)Restaurant Row crowd is loud and caffeinated. Many bars open early with mimosas and Bloody Marys.
All Race Distances
| Distance | Start Time | Course | Fee | Cutoff |
|---|---|---|---|---|
| Marathon (26.2 mi) | 6:00 AM | Full out-and-back on Colfax | $130–$160 | 6h 30m |
| Half Marathon (13.1 mi) | 6:30 AM | Eastern half with Zoo Mile | $100–$130 | 4h 00m |
| 10 Miler | 7:00 AM | Western loop via Empower Field | $80–$100 | 3h 00m |
| 5K (3.1 mi) | 7:30 AM | City Park loop | $45–$60 | 1h 30m |
| Marathon Relay (5 legs) | 6:00 AM | Full marathon, 5 exchanges | $300–$400/team | 6h 30m |
Frequently Asked Questions
There’s nothing like running through Mile High Stadium with 70,000 empty seats cheering in your imagination, then finishing at Ferril Lake with the real crowd roaring. Colfax is magic.
— 2024 Colfax Marathon finisher
Ready to Run the Mile High City?
Registration for the 2026 Denver Colfax Marathon is open. Secure your spot before prices increase.
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