40/50 Mile Challenge | Half Day Forest Preserve
August 29,, 2026
Location: Half Day Forest Preserve
24255 N Highway 21
Vernon Hills, IL 60061
Distances Offered: 40 Mile, 50 Mile
Half Day Forest Preserve –
Vernon Hills, IL
The course at Half Day Forest Preserve offers runners a beautiful mix of open prairie, mature woodlands, scenic ponds, and river-bottom forest along the Des Plaines River corridor. Athletes will complete a clearly marked loop that returns each lap to the same centralized start/finish area and fully stocked aid station, making it easy to manage pacing, fueling, crew support, and race strategy throughout the day.
The terrain is predominantly flat and fast, featuring a combination of crushed limestone, gravel, and well-maintained natural trails. The course winds through quiet forest preserves, passes scenic ponds and wetlands, and connects with sections of the renowned Des Plaines River Trail. The smooth footing and gentle elevation profile make the course approachable for first-time trail runners while still providing an enjoyable endurance challenge for experienced ultra runners.
Runners will experience a diverse natural landscape that includes oak savannas, prairie restoration areas, wetlands, and riverfront habitats. Wildlife sightings are common, and the preserve's peaceful setting creates a feeling of being immersed in nature despite its convenient location in the Chicago suburbs. The combination of open views, shaded forest sections, and riverside scenery provides a constantly changing backdrop throughout the event.
The loop-based format allows participants to focus on their individual goals, whether that's completing a first trail race, reaching a new distance milestone, or pushing through an all-day endurance effort. With frequent access to aid, personal gear, and crew support, runners can spend less time worrying about logistics and more time discovering how far they can go.
Your Endurance. No Limits. One More Loop.
The 40/50 Mile Challenge
The 40/50 Mile Challenge is a continuous loop endurance race designed for runners who want to push beyond traditional race formats while benefiting from a fully supported, centralized course.
Held alongside The Next Loop Endurance Series, this event runs on the same 3.1-mile (5K) loop, but unlike the hourly format, competitors in the 40/50 Mile Challenge run continuously with a strict time cutoff.
This format offers a true ultra-distance experience—simplified logistics, consistent footing, and constant access to aid and support.
Event Format
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Distances: 40 Miles or 50 Miles
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Loop Length: 3.1 miles (5K)
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Course Type: Continuous loop trail race
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Time Limit: 12 hours
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Start/Finish: Same location each loop
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Aid Station: Fully stocked at every lap
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Staging Area: Designated personal staging area near start/finish
Runners complete repeated loops until they reach their chosen distance or the time limit expires.
Who Should Run the 40/50 Mile Challenge
This event is ideal for:
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Runners attempting their first ultra distance
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Athletes stepping up from a marathon or 50K
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Experienced ultrarunners seeking a fast, efficient course
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Competitors who value logistics simplicity and strong support
The loop format removes navigation concerns and allows athletes to focus entirely on pacing, fueling, and mental toughness.
Support & Logistics
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Runners may access personal supplies at their staging area each loop
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Crew access permitted in designated areas
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Pacers allowed per event rules (location-specific and time-based)
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Medical and race staff on site throughout the event
This setup allows runners to adapt strategy on the fly—fueling, gear changes, and rest without leaving the course.
Running Alongside The Next Loop, The 40/50 Mile Challenge runs simultaneously with The Next Loop Endurance Series on the same course.
While Next Loop participants run on the hour, 40/50 Mile Challenge runners race continuously and are scored separately.
Each event has its own competitive field, results, and rules.This creates an energetic race environment while preserving the integrity of both formats.
Ready to Take on the Challenge?
Registration is limited to ensure course quality and runner support.