Loud Thunder 50

Event

Loud Thunder 50 takes place on Saturday, April 18, 2026, at Loud Thunder Forest Preserve in Illinois City, IL. The event offers three trail distances:

• 50 Miler
• 50K
• 1/2 Marathon

The start/finish area is at the Horse Corral Campground. Camping is available at that campground and others in the park; online campground reservations have a two-night minimum while unreserved sites are first come, first served with a one-night minimum.

Course and logistics

The main race loop is about 13.3 miles and the course is primarily trail - approximately 95% trail with dirt single and double track, short grass and crushed gravel connectors, and minimal pavement. Elevation gain is approximately ~6600 ft for the 50 mile, ~4000 ft for the 50K, and ~1900 ft for the half marathon. The 50 mile runs the full route three times plus a shortened fourth loop, the 50K runs two full loops plus a shortened loop, and the half marathon completes a single loop. The embedded loop map follows the 50K directional flow.

Two fully stocked aid stations are on course; the longest gap between aid stations is under 5 miles. Both allow drop bags and crew access. Pacers are allowed only for the 50 mile and only for the final ~18 miles.

Rules and registration

Registration is online only. There are no refunds or bib transfers. Deferral credits are available with deadlines: 100% deferral by February 18 and 50% deferral by March 18. Key event rules include Leave No Trace, no course cutting, trekking poles allowed, no dogs on course, strict enforcement of cutoffs, no muling, one pacer at a time, and respect for other trail users. 50 mile finishers within the official cutoff receive a finisher hoodie and a special patch. Visit the organization's website for the most recent information.