About This Race
The Colossal Vail 50/50 presents a compelling introduction to high desert trail running on portions of the Arizona National Scenic Trail near Vail, southeast of Tucson. Starting and finishing at Colossal Cave Mountain Park, this race showcases expertly built trail through the transition zones between the Sonoran Desert and the Mexican Highlands, where plant communities shift from towering saguaro forests to yucca grasslands. The course was designed by experienced members of the Tucson Trail Runners as a relatively fast trail ultra on rolling terrain with expansive vistas of surrounding mountain ranges. The race utilizes passages 7 and 8 of the Arizona Trail, constructed within the past 15 years specifically for trail use rather than repurposed existing paths. Runners traverse ancestral lands of the Tohono O'odham and Pascua Yaqui peoples while experiencing the varied ecosystems of Arizona's Sky Islands region. The relatively gentle terrain compared to nearby mountain trails, combined with comprehensive aid station support and well-marked courses, makes this an accessible yet engaging ultra experience in one of Arizona's most scenic desert environments.
The out-and-back course begins at La Posta Quemada Ranch and climbs 0.23 miles to intersect the Arizona Trail proper. Runners head south through limestone formations and small canyon crossings, with views of Cienega Creek's riparian corridor. Key landmarks include the Three Bridges area where the trail passes under railroad bridges and crosses Marsh Station Road, followed by a descent to the course's low point at Cienega Creek (3,300 feet). The route continues through Davidson Canyon, passes under I-10 via tunnel, and crosses rolling country with expansive vistas before reaching Highway 83.
Terrain varies from gentle rolling hills to moderate climbs, with the trail surface consisting of well-maintained singletrack. The course features few completely flat sections, providing consistent but manageable challenge throughout. Notable features include passage through red pineapple cactus forests, views of Davidson Canyon, and the transition from saguaro-dominated landscapes in the north to more diverse desert scrub communities in the southern sections.
Aid Stations
1 stations along the course
Gabe Z Trailhead
water, electrolyte, food
First aid station at 4.9 miles
Practical Info
December desert conditions with cool morning temperatures and mild daytime highs, typical of Arizona winter running weather.
TUS - Tucson International Airport
Located 24 miles southeast of Tucson with various lodging options in the greater Tucson area.
Best For
Notable Features
This race is distinguished by its use of purpose-built Arizona Trail sections through diverse high desert ecosystems, from saguaro forests to yucca grasslands. The cupless event format demonstrates environmental consciousness, while the course's role as the first event in the Southern Arizona Triple 50 series adds significance for ultra series participants. Well-stocked aid stations, comprehensive emergency communications, and excellent event organization create a supportive environment for runners attempting their first ultra or seeking a scenic desert challenge.