 All of US 15 except the portion between Catoctin Furnace and Thurmont is part of the Journey Through Hallowed Ground Byway, which was designated a National Scenic Byway in September 2005.The entire length of the highway in Maryland is part of the National Highway System.US 15 enters Maryland at Point of Rocks, named for the pair of mountain peaks between which the Potomac River cuts through Catoctin Mountain, Pine Rock in Maryland and Furnace Mountain in Loudoun County, Virginia.