40/50 Mile Challenge - Half Day Forest Preserve
Lincolnshire, United States • 29 Aug 2026
40/50 Mile Challenge at Half Day Forest Preserve
The 40/50 Mile Challenge is a continuous loop trail race held at Half Day Forest Preserve in Vernon Hills, Illinois. The course uses a clearly marked 3.1 mile loop that returns each lap to the same centralized start and finish area. Distances offered:
- 40 Mile
- 50 Mile
The terrain is predominantly flat and fast with crushed limestone, gravel, and maintained natural trails. The route passes open prairie, oak savanna, mature woodlands, scenic ponds, wetlands, and river-bottom forest along the Des Plaines River corridor, and connects with sections of the Des Plaines River Trail. Footing is generally smooth and the elevation profile is gentle.
The event format is continuous running with a 12 hour time limit. A fully stocked aid station is available on every lap. Runners have a designated personal staging area near the start and may access personal supplies each loop. Crew access is permitted in designated areas and pacers are allowed according to event rules. Medical and race staff are on site throughout the event.
This race runs simultaneously on the same course as The Next Loop Endurance Series. Next Loop participants run on the hour while 40/50 Mile Challenge runners run continuously and are scored separately. Visit the organization's website for the most recent information.