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I'm Bound for Boston Marathon & Half Marathon - Denver
A loop course built to qualify you for Boston
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Wild West Relay
200-mile relay over Colorado mountain passes to Steamboat
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Aspen Backcountry
Dirt trails and big climbs beneath the Elk Mountains of Aspen
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Rocky Mountain Half & 5K
Half marathon by the lake near Rocky Mountain National Park
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Kennebec Mountain Run
Trail race over 12,000-foot Kennebec Pass in La Plata Mountains
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Winter Park 50K
High-country trails above Winter Park, Colorado
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Run the Rockies Trail-5K, 10K and Half Marathon
Frisco Peninsula trail with Dillon Reservoir views
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Pyro's Push It Up Trail Run
Trail run through Colorado's Flat Tops Wilderness
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Georgetown to Idaho Springs Half Marathon
A net-downhill point-to-point through Clear Creek Canyon
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Leadville Trail 10K
A high-altitude 10K along the legendary LT100 course
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Sunrise Stampede
Now in its 40th year on Longmont's open space trails
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Just Peachy 5K & 10K
Finishes with a peach at Palisade's Peach Festival
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Telluride Mountain Run
A mountain ultra through Telluride's San Juan peaks
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Mount Sneffels Half Marathon & 10K
Mountain racing through Colorados Switzerland of America
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Boulder Rez Marathon
Flat course circling Boulder Reservoir with Rockies views
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Boulder Sunset 10K & 5K Run
Crosses the Boulder Reservoir dam with a downhill finish
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Byers Peak Stampede Half Marathon & 5K
All-dirt trail through Arapaho National Forest
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Thirsty 13 Half Marathon
Downhill finish at Ska Brewing in Durango
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Leadville Trail 100
One hundred miles above two miles high in the Rockies
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Continental Divide Trail Run
Out-and-back along the Continental Divide
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Rock Hawk Trail Races
Peaks near 6,635 ft on Castle Rock's Ridgeline Trail
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Arrowhead Half Marathon & 5K
Climbs to 9,560 feet atop Bachelor Gulch, then descends
Save any of these to your season in RunCalendar and hear the morning entries open. Free on iPhone, no account needed.
Every race here is published by its organiser; RunCalendar checks the date and the entry window against the organiser's own page and rebuilds this calendar every night. A confirmed date shows its day; a provisional one shows only its month. Last updated 22 October 2026.