U.S. Route 15 (
US 15) is a part of the
U.S. Highway System that runs from
Walterboro, South Carolina to
Painted Post, New York. In
Maryland, the highway runs from the
Virginia state line at the
Potomac River in
Point of Rocks north to the
Pennsylvania state line near
Emmitsburg. Known for most of its length as
Catoctin Mountain Highway, US 15 is the primary north–south highway of
Frederick County. The highway connects the
county seat of
Frederick with Point of Rocks,
Leesburg, Virginia, and
Charles Town, West Virginia (via
US 340), to the south and with
Thurmont, Emmitsburg, and
Gettysburg, Pennsylvania, to the north. US 15 is a four-lane divided highway throughout the state except for the portion between the
Point of Rocks Bridge and the highway's junction with US 340 near
Jefferson. The U.S. Highway is a freeway along its
concurrency with US 340 and through Frederick, where the highway meets
US 40 and
Interstate 70 (I-70). US 15 has an
unsigned business route through Emmitsburg.