Trail Running Races in the Rocky Mountains

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The Rocky Mountains have shaped American ultrarunning more than any other range — Hardrock, Leadville, Run Rabbit Run, and dozens of races below the bucket-list tier all live here. The combination of altitude (most races start above 7,000 feet, many finish above 12,000), big vertical, and unpredictable summer thunderstorms makes Rocky Mountain trail races a test of fitness, planning, and respect for weather. We catalog every trail race we can find across Colorado, Wyoming, Montana, Idaho, and Utah — from 10ks to the legendary 100-mile circuit. Filter by distance, elevation profile, and date below.

Frequently asked

  • When is the trail running season in the Rocky Mountains?
    Mid-June through late September is the core window. Snow lingers on high passes into July most years, and afternoon thunderstorms get aggressive from mid-July through mid-August. The shoulder weeks of late June and mid-September are popular for that reason — fewer storms, drier trails.
  • How much does altitude affect race performance?
    A lot more than most flatland runners expect. Above 8,000 feet plan for a 10–20% drop in sustainable pace; above 12,000 feet it can be 25–35%. Arrive at altitude either the day before (race on travel-fresh legs) or 7+ days early (start acclimatizing). Three to four days out is physiologically the worst window — you'll feel the altitude without having adapted to it.
  • How dangerous are afternoon thunderstorms?
    Serious. Above tree line, lightning is the real threat — multiple fatalities most years across the range. Most well-run races have cutoffs designed to get runners off exposed ridges by 1pm. If you're slower than the cutoff, take the early start option. Carry a lightweight rain shell even in clear weather.
  • Which Rocky Mountain races are good qualifiers for Western States or UTMB?
    Run Rabbit Run 100 (CO), Bighorn 100 (WY), the Bear 100 (UT/ID), and Wasatch 100 (UT) all carry Western States lottery tickets. Hardrock has its own qualifier system. For UTMB Index, Run Rabbit Run and Tushars Mountain Runs (UT) both rank well.
  • What gear is non-negotiable for Rocky Mountain races?
    A waterproof shell (not just water-resistant), gloves, hat, and a headlamp for any race that could extend past sunset. Most race directors mandate at least the shell and headlamp. Add an emergency blanket and electrolyte tablets even if not required — high-altitude weather flips fast and aid stations are often farther apart than in lower-altitude events.