40/50 Mile Challenge - Deer Grove East
Deer Park, United States • 8 Aug 2026
40/50 Mile Challenge - Deer Grove East
The 40/50 Mile Challenge is a continuous loop trail race held at Deer Grove East Forest Preserve in Palatine, IL. Runners repeat a clearly marked 3.1 miles loop (5K) that returns to the same centralized start and finish area on every lap. The event offers fully stocked aid at the central station on each lap and a designated personal staging area for supplies and gear.
The course runs through restored prairie, open wetlands, oak savannas, and shaded woodlands. Terrain is primarily flat to gently rolling with a mix of paved and natural-surface trails that provide consistent footing. The preserve is noted for its grasslands, wetlands, savannas, and wildlife; runners may encounter deer, native birds, and seasonal wildflowers along the route.
Support and logistics include crew access in designated areas, allowance for pacers according to event rules, and medical and race staff on site. The format is continuous running toward a set distance with a strict time limit of 12 hours, so athletes complete repeated laps until they reach their chosen distance or the cutoff.
Suggested participants include athletes attempting their first ultra distance, runners moving up from a marathon or 50K, and experienced ultrarunners seeking repeated-loop racing with centralized support. Visit the organization's website for the most recent information.
- 40 Mile
- 50 Mile