Colfax Marathon: a rolling loop course in Denver. Pacing by section, fueling, and race-day tips.
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The Colfax Marathon is a city marathon in Denver. It starts and finishes in City Park and is a Boston Marathon qualifier. The route follows Colfax Avenue, Sloan's Lake and the Cherry Creek Trail, and runs through the Empower Field at Mile High stadium twice.
| Fact | Value |
|---|---|
| Location | Denver, Colorado, USA |
| Distance | 42.195 km (marathon) |
| Usually held | May |
| Course | rolling, loop |
| Official site | https://www.runcolfax.org/ |
The official course guide describes flat and fast middle miles, a downhill section around miles 16–20, and an uphill road out of downtown near the end. Start at an even effort and keep energy for the last 6 miles.
| Section | Terrain | Advice |
|---|---|---|
| mile 1–6.5 | Colfax Avenue, downtown and the Cherry Creek Trail | Hold goal pace or slightly slower while the crowds are thick. |
| mile 6.5–10 | Short climb out of the stadium, then flat Colfax and Sloan's Lake | Ease up the short climb and settle back into goal pace on the flat road. |
| mile 10–16 | West on Colfax, then Lakewood and The Glens | Stay relaxed and keep a steady effort. |
| mile 16–20 | Downhill on Colfax from Lakewood back to Denver | Let the pace come down a little, but keep your stride short to protect your legs. |
| mile 20–26.2 | Stadium, river path, 16th Street Mall, uphill on 17th Avenue, then City Park | Run by effort on the uphill part of 17th Avenue and save a push for City Park. |
The race site lists water and Gatorade every 2 miles and Honey Stinger gels at miles 6 and 20. Plan your own gels around those points.
The official guide calls the Sloan's Lake section flat and fast, but it also lists a short climb out of the stadium, a downhill section from Lakewood and an uphill stretch on 17th Avenue. No elevation figures are published on the page we checked.
Both are in Denver's City Park. The start is on the east side of Ferril Lake and the finish is between Ferril Lake and the Museum of Nature and Science.
It is usually held in May, on a Sunday.
Facts checked 2026-10 against the sources below. Race details change from year to year — confirm with the official site before race day.
Every public page on this site has a Markdown mirror at the same path with a .md suffix (for example /calculator.md), and honors an Accept: text/markdown request header on the HTML URL. The calculations here are also available as callable tools through a free public MCP server — no account or API key.