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Palmer Lake July 4th - 4M
Palmer Lake's 43rd annual school fundraiser run
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3.6 Mile Fun Run
Loops the golf course, finishes at the tavern
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Hahn's Peak Vertical Trail Race
A summit dash to Hahns Peak's old fire lookout
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Boogie's Buddy Race
40 years of runners and dogs in Aspen
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Loveland Liberty
Starts at Grimm Brothers Brewhouse in Loveland
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Let Freedom Run 5k/10k - Louisville
Runners dress as their favorite American hero
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Vail HillClimb
A steep climb up the slopes above Vail Village
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Silverheels Trail Runs
Runs past ghost towns beneath Silverheels Mountain
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Hardrock 100
Wild high altitude loop through the San Juan Mountains
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Silver Rush 50 Run
Leadville's high-altitude 50-miler through old mining country
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All-Out Dog Days
Big Dry Creek Trail miles with Flatirons views
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Grin & Bear It
Crested Butte's oldest trail race, to Green Lake
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High Lonesome 100
Crosses 12,000ft passes in the Collegiate Peaks
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10@10 Vail Mountain Race
High altitude 10K on Vail Mountains legendary back bowls
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Ouray 100 Mile Endurance Run
100 miles through Colorado's rugged San Juan Mountains
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Silverton Alpine Marathon
Alpine Loop jeep roads past San Juan mining ghost towns
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Donor Dash
Loops through Denver's Washington Park lake trails
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Aspen Valley Marathon
High altitude miles amid forest and mountain around Aspen
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Barr Trail Mountain Race
Climbs the historic Barr Trail toward Pikes Peak
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Kendall Mountain Run
A raw climb from Silverton to the Kendall summit
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Never Summer 100k & 60k
Trails beneath Colorado's Never Summer mountain range
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Pikes Peak Ultra
Winds through Cheyenne Canon on the trails of Pikes Peak
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Box Canyon Trail Races
Alpine loops above Telluride cresting 13,000 feet in the San Juans
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The 2026 "Spirit of the West" 5K run/walk, benefitting Westernaires
A hilly 5K in the foothills of Golden, Colorado
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The Summit 200
Summit County's inaugural 200-mile Rockies ultra
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TransRockies Run - Pass to Pub
A three-day stage race through the Colorado Rockies
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Creede 50/100
High alpine San Juan Mountains ultra above Creede
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MOUNTAIN FAIR 4-MILER
Carbondale's Mountain Fair 4-Miler with Mt. Sopris views
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Grand Mesa Ultras
Races across Grand Mesa, the largest flat-topped mountain on Earth
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.