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High Lonesome 100
Race Details:
- Location: Nathrop, CO, USA
- Race Date: 07/17/2027
- Race Distances: 100 Mile, Ultra Marathon
What This Race Counts Toward:
Western States 100: Yes
UTMB Index: No
High Lonesome 100 Description
The High Lonesome 100 is a rugged 99.8-mile loop course through the Sawatch and Mosquito ranges near Nathrop, Colorado, organized by Freestone Endurance. Runners climb roughly 22,500 feet, cresting a 13,150-foot high point along the Continental Divide before descending to an 8,150-foot low point. Entry is decided by an annual lottery, with a Trail Mix Fund supporting equitable access for underrepresented runners. The race is a Western States Endurance Run qualifier, drawing competitive fields to test themselves against Colorado’s high alpine terrain and thin air.
Always check the official race website for the most accurate and up-to-date race information and logistics.
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High Lonesome 100 Additional Details:
High Lonesome 100 takes a firm stance against UTMB Group-owned races, explicitly excluding any UTMB Index race from its own qualification requirements due to the promoter’s partnership with Ironman, a rare and outspoken position in the ultrarunning qualifier landscape. The course is roughly 66% singletrack, 20% mining roads, and 10% gravel, with a 37-hour cutoff. Pacers may join at Hancock (mile 49.3) and any subsequent crew-accessible aid station, but must carry all required gear themselves and cannot carry anything for their runner. Required gear includes standard mandatory items plus a CORSAR card for pacers. Drop bags and full crew access are permitted at select aid stations. The race caps its field size in coordination with the U.S. Forest Service and relies on a strict qualifying-race list rather than a time standard.
Course Information
Profile: Very Hilly
Type: Loop
Surface: Road/Pavement, Trails
Pace Groups: No
Time Limit: 37 hr
# of Finishers
100 Mile: 166 finishers (2025)
Elevation Details
Elevation Gain: 22,500 ft
Elevation Loss: 22,500 ft
Average Temperature
- Low: 48°F
- High: 85°F
Train Smarter for Race Day
A great race starts long before the starting line. Whether you’re chasing your first finish or hunting a new PR, a structured training plan takes the guesswork out of race prep — building your fitness, your confidence, and your mileage at the right pace for you.
Explore plans for every distance and experience level, from your first 5K to your next ultra.
Things to Do in Nathrop, CO, USA
Make the most of race weekend — here’s how to fill the time before and after you cross the finish line.
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