40/50 Mile Challenge - Half Day Forest Preserve
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40/50 Mile Challenge - Half Day Forest Preserve
The 40/50 Mile Challenge is a continuous loop trail race held at Half Day Forest Preserve in Vernon Hills, IL (24255 N Highway 21). Competitors run repeated laps of a clearly marked 3.1 mile (5K) loop until they reach their chosen distance or the event time limit.
Distances offered:
- 40 Mile
- 50 Mile
The course passes open prairie, mature woodlands, scenic ponds, wetlands, and river-bottom forest along the Des Plaines River corridor. Footing is a mix of crushed limestone, gravel, and well-maintained natural trails. The terrain is described as predominantly flat with a gentle elevation profile. The route connects with sections of the Des Plaines River Trail and includes oak savannas and prairie restoration areas. Wildlife sightings are common.
Logistics are centralized each lap with the same start and finish area, a fully stocked aid station at every lap, and a designated personal staging area near the course. Crew access is permitted in designated areas and pacers are allowed per event rules. Medical and race staff are on site during the event. The format runs alongside The Next Loop Endurance Series on the same loop; 40/50 Mile Challenge participants run continuously and are scored separately. There is a 12 hour time limit. Registration is limited to preserve course quality and runner support. Visit the organization's website for the most recent information.
