Sloan's Lake Search Party (SLSP) Marathon Hourly Loop Race

The Frederick Pack Burro Race is an annual 10K event held in Frederick, Colorado, celebrating the town's Miners Day heritage. The race follows a scenic course starting downtown at Fifth and Oak Streets, heading north along a trail through a tunnel to the Frederick Recreation Area, looping around Mil..

The Bear Chase Race Endurance Festival occurs at Bear Creek Lake Park in Lakewood, Colorado, offering 100K, 50 Mile, 50K, Half Marathon, 10K, and 5K (plus the Baby Bear 10K). The mostly dirt, single-track course is described as fast by trail/ultra standards and rewards sweeping mountain views with c..

The Castle Rock Trail Festival / liveBIG Run is a trail running and walking event on the Ridgeline trail system in Castle Rock, using Philip S. Miller Park and Ridgeline Open Space. The event includes a family obstacle run for children ages 5 to 12 and longer trail races for adult participants. Par..

Suffer Better Fall Trail Runs take place at Staunton State Park, just off Highway 285 near Conifer, Colorado. The event offers four distances: 50K, 25K, a 25K FishSlappers edition, and a new 5K. The course showcases CO’s best trails—lovely, flowing singletrack with significant vertical gain (roughly..

Boulder XC Series Meet 1 is a family-friendly cross-country event held at Valmont City Park (South) in Boulder, Colorado (5110 Valmont Rd). The meet offers three distances: 1K for younger runners, 3K for those up to 16, and a 5K open race, welcoming participants of all ages and abilities. It’s the f..

Indian Creek Trail Runs, the oldest official race in the Human Potential Running Series, is held at Indian Creek Campground in Sedalia, Colorado. The 12th annual Fall Classic offers four distances — 5-Mile, 15-Mile, 55k, and 50-Mile — with a combined cap of 225 runners. Runners traverse seldom-used..