 North of its intersection with Blue Mountain Road and Pryor Road, US 15 leaves the park boundary and enters the town of Thurmont.The U.S. Highway has a diamond interchange with unnamed and unsigned MD 15C that leads to the northern end of MD 806 and to Frederick Road, which serves a commercial area south of downtown Thurmont.US 15 continues north to a folded diamond interchange with MD 77 (Main Street) where the highway also crosses Hunting Creek; MD 77 follows the creek up the mountain as Foxville Road toward Catoctin Mountain Park.