Take a hike on National Trails Day. American Hiking Society's National Trails Day is a celebration of America's magnificent trail system, occurring annually on the first Saturday in June. Cass Scenic Railroad State Park's interpreter will be leading a hike down the beautiful Greenbrier River Trail State Park. Departing from the Visitor Center, this hike will roughly be 3 miles round trip on a flat, crushed gravel surface. This hike takes 1 hour and 30 minutes to complete, dress for the weather and bring water!