Fs 451.1 is a hiking, biking, and horse trail in Boulder County, Colorado. It is within Roosevelt National Forest. It is two miles long and begins at 8,420 feet altitude. Traveling the entire trail is 4.0 miles with a total elevation gain of 1,299 feet. The Copper King Mine (elevation 8,307 feet) and Seven-Thirty Mine (elevation 8,412 feet) quarries can be seen along the trail.