Following the old Fernley and Lassen Branch Line of the Southern Pacific railroad, the trail winds 25.4 miles from Susanville to Mason Station. For the first 16 miles, the trail follows the Susan River. As it winds through the rugged Susan River Canyon, the trail crosses the river 12 times on bridges and trestles and passes through two tunnels.
The landscape is a combination of semi-arid canyon and upland forests of pine and fir. The trail then follows existing roads an additional 4.5 miles into Westwood, where a railroad station type kiosk and a 25-foot carved redwood statue of Paul Bunyan mark the Westwood trailhead.
The trail has four distinct seasons because of the high elevation location.