National Forest Development Road 400 is a hiking, biking, and horse trail in White Pine County, Nevada. It is within Humboldt-Toiyabe National Forest. It is 18.9 miles long and begins at 8,247 feet altitude. Traveling the entire trail is 38.0 miles with a total elevation gain of 4,172 feet. The Illipah Creek Reservoir (elevation 6,795 feet) reservoir can be seen along the trail.