The Leadville Trail Marathon and Heavy Half 2026 is arguably the nation’s toughest and highest-altitude marathon. The route takes trail runners through the historic mining district’s challenging trails to the highest point of any Leadville Race Series event: Mosquito Pass (13,185 feet). As you take on the toughest trails and thinnest air in all of endurance racing, you’ll need all the grit, guts, and determination you can muster.

This event is part of the Leadville Trail Qualifier Series and is rated by Strambecco as one of the Best Trail Running events in the Rockies.

Leadville Trail Marathon: The Leadville Trail Marathon covers approximately 26.2 miles (42.2 kilometers) through the rugged and picturesque Rocky Mountains each year. The course features a mix of single-track trails, steep ascents, technical descents, and physically and mentally challenging runners. Participants must navigate rocky paths, dense forests, and alpine meadows while tackling an elevation gain of over ~6,000 feet (1,800 meters). The race starts and finishes in downtown Leadville, taking runners on a breathtaking journey through the heart of Colorado’s wilderness.

Leadville Trail Half Marathon: The Leadville Trail Half Marathon covers approximately 13-15 miles (21-24 kilometers) and shares a significant portion of the marathon course. It provides a slightly less grueling but demanding experience for runners seeking a shorter distance or less strenuous challenge. Despite being a half marathon, participants still face significant climbs (over ~3,400 ft) and technical terrain, traversing the same awe-inspiring trails as the marathon runners.

Both races occur in mid-summer when the weather in Leadville is generally pleasant. Still, runners should be prepared for varying conditions and sudden weather changes, as the high altitude can bring about rapid shifts. Aid stations are strategically placed along the course, offering hydration, nutrition, and medical support to ensure the safety and well-being of participants.

Each Leadville Qualifying Series race provides up to 25 slots for the Leadville Trail 100 Run, based on the total number of registered runners at each qualifier event. Twenty qualifying spots will be allocated based on the top age-group performances. Five will be drawn among runners who have finished the qualifier race within the allocated cutoff time.

The Leadville Race Series started in 1983 with just one race through the Rocky Mountains. Produced by Life Time Events, it has expanded in the United States with multiple running and biking events.