Loud Thunder 50

Event details

Loud Thunder 50 takes place on April 18, 2026 at Loud Thunder Forest Preserve in Illinois City, IL. Distances offered are:

• 50 Miler
• 50K
• 1/2 Marathon

The start/finish area is at Horse Corral Campground near 19408 Loud Thunder Rd. Registration is online only and closes April 1. The event is organized by Sun Trail Running. Packet pickup is handled on race morning and packets are not shipped. There is a deferral policy with deadlines for partial or full credit; refunds and bib transfers are not offered.

Course and logistics

The primary race loop is about 13.3 miles and the course is mostly trail - approximately 95% trail with dirt single- and double-track, short grass and crushed gravel connectors, and minimal pavement. Elevation gain is listed as about 6600 ft for the 50 mile, about 4000 ft for the 50K and about 1900 ft for the half. The 50 mile does three full loops plus a shortened fourth loop, the 50K does two full loops plus a shortened loop, and the half marathon does a single loop. Course direction varies by distance.

Two fully stocked aid stations are used, both allowing drop bags and crew access; the longest gap between aid stations is under 5 miles. Pacers are allowed only for the 50 mile and only for the final roughly 18 miles. Camping is available at Horse Corral Campground and other park campgrounds; online campsite reservations have a two-night minimum while unreserved sites are first come first serve with a one-night minimum. Key rules include Leave No Trace, no cutting the course, trekking poles allowed, dogs prohibited, strict cutoff enforcement, and no bib transfers. 50-mile finishers who complete within the official 14-hour cutoff receive a finisher hoodie on their first 50-mile finish and patches for subsequent finishes. Visit the organization's website for the most recent information.