40/50 Mile Challenge | Half Day Forest Preserve

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 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
Distances: 40 Miles or 50 Miles

Loop Length: 3.1 miles (5K)

Course Type: Continuous loop trail race

Time Limit: 12 hours

Start/Finish: Same location each loop

Aid Station: Fully stocked at every lap

Staging Area: Designated personal staging area near start/finish

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Runners complete repeated loops until they reach their chosen distance or the time limit expires.

​Who Should Run the 40/50 Mile Challenge
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This event is ideal for:

Runners attempting their first ultra distance

Athletes stepping up from a marathon or 50K

Experienced ultrarunners seeking a fast, efficient course

Competitors who value logistics simplicity and strong support