Prepare for a true test of trail running at the Castlewood Cup 15K, returning for its 18th year on Saturday, January 31, 2026, at Castlewood State Park in Missouri. This challenging 15K race promises an exhilarating experience across Castlewood's renowned single track, featuring a dynamic course filled with uphills, downhills, and switchbacks that will test your grit and skill. With approximately 965 feet of elevation gain, equating to the energy expenditure of running a flat 10.5 miles, this course is predominantly un-paved, traversing rugged terrain with roots and rocks, offering both a physical challenge and breathtaking scenery along the Meramec River floodplain. Typical race day conditions in late January often see highs around 47F and lows near 25F, with a low chance of precipitation, providing crisp winter air for your adventure.

Runners can anticipate a well-supported event with on-course hydration stations and wave starts beginning at 10 AM, with a 3-hour course cutoff time ensuring all participants have ample opportunity to conquer the trail. Known for its vibrant atmosphere, the Castlewood Cup extends the excitement beyond the finish line with a celebratory post-race party. Participants can look forward to a delicious BBQ lunch, refreshing beer (for those 21 and over), and live music, weather permitting. Every finisher receives a custom medal, and a race sweatshirt to commemorate their accomplishment, with age group awards and gift cards for overall top male and female runners.

The Castlewood Cup, part of the esteemed Big River Trail Series, has cultivated a reputation as a favorite among trail enthusiasts, celebrated for its challenging course and rewarding post-race festivities. Join fellow runners to break up the winter monotony and immerse yourself in one of Missouri's most scenic and well-maintained trail experiences.