About This Race
The Colossal-Vail 50/50 offers a welcoming entry point into desert ultrarunning, utilizing a scenic section of the Arizona Trail near Tucson. Organized by experienced members of the Tucson Trail Runners and presented by Fleet Feet Tucson, this December event was specifically designed to give new ultra runners the best chances of completion while providing a satisfying challenge for experienced trail runners. The race takes place on the ancestral lands of the Tohono O'odham in the high desert landscape east of Tucson. What sets this race apart is its thoughtful approach to both environmental stewardship and runner experience. The event has adopted a cupless format to reduce environmental impact, and proceeds benefit the Arizona Trail Association. The unique course design allows 50-mile runners who reach the 55K turnaround to receive finisher's credit for that distance if they choose not to continue, providing a built-in bailout option. Every ultra finisher receives an engraved railroad spike, while half-marathoners earn a wooden finisher award. Runners should be aware that Africanized bees can be prevalent during some years, and the race organizers have implemented mitigation strategies while advising allergic individuals to consider other events. The race features five well-stocked aid stations managed by experienced ultra runners who understand what trail runners need during long efforts.
The course begins at La Posta Quemada Ranch in Colossal Cave Mountain Park, heading south along the scenic eastern boundary between the Sonoran and Chihuahuan Deserts. Runners experience striking vistas and open spaces as they reach the northernmost ridges of the Santa Rita Mountains before returning to the ranch. The 50-mile distance continues north on the Arizona Trail for an additional eight miles before the final turnaround back to the finish line.
The fast and fun terrain features two out-and-back segments that showcase the high desert's natural beauty. The course design emphasizes accessibility while maintaining the authentic trail running experience that the Arizona Trail is known for, with the route positioned strategically to take advantage of the dramatic landscape where two major desert ecosystems meet.
Location
Aid Stations
1 stations along the course
Aid Station
water, electrolyte, food
Five total aid stations along the routes, four of which are used twice by runners. Well-stocked and managed by experienced ultra runners. Skratch Labs is the official hydration sponsor.
Practical Info
December in the Arizona high desert typically offers ideal running conditions with cool mornings, mild daytime temperatures, and clear skies.
TUS - Tucson International Airport
Plenty of lodging available in nearby Tucson, with some guest houses and ranches in Vail. Camping is encouraged with space available near the start/finish line.
- Reusable cup or bottle
Best For
Notable Features
This race stands out for its beginner-friendly approach to ultrarunning while maintaining authentic trail character. The unique distance option allowing 55K credit for 50-mile entrants, combined with the cupless environmental initiative and proceeds benefiting the Arizona Trail Association, reflects thoughtful race organization. The December timing provides ideal desert running weather, and the distinctive finisher awards—engraved railroad spikes for ultra distances—celebrate the completion achievement.