U.S. Route 15 (US 15) is a part of the United States Numbered Highway System that runs from Walterboro, South Carolina, north 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 an expressway throughout the state except for the portion south of MD 28. The 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 a business route through Emmitsburg.
US 15 is the descendant of a pair of turnpikes that connected Frederick with Emmitsburg to the north and Buckeystown to the south. These turnpikes were reconstructed as state roads in the 1910s north of Frederick and in the early 1920s from Frederick south to Tuscarora. When US 15 was assigned in 1927, the Tuscarora–Point of Rocks highway had yet to be improved; this section was paved in the early 1930s. The modern Point of Rocks Bridge was built in the late 1930s after its predecessor was destroyed in a flood. The Frederick Freeway was constructed in the 1950s. US 15 was relocated to part of the freeway; the old route of the U.S. Highway through downtown Frederick became part of Maryland Route 355 (MD 355). US 15's present highway between Point of Rocks and Jefferson was constructed in the late 1960s; the old road south of Frederick was replaced with MD 28 and MD 85. North of Frederick, the U.S. Highway bypassed Thurmont and Emmitsburg in the late 1950s and mid-1960s, respectively. US 15 was upgraded to a divided highway north of Frederick in the early 1980s.
Route description US 15 has several official designations throughout its course in Maryland. The U.S. Highway is known as Catoctin Mountain Highway from the Virginia state line at Point of Rocks north to US 340 near Jefferson and from MD 26 in Frederick north to the Pennsylvania state line near Emmitsburg. US 15 is also part of Jefferson National Pike along its freeway concurrency with US 340 and the Frederick Freeway between US 340 and MD 26. In July 2004, the Maryland General Assembly designated the highway the 115th Infantry Regiment Memorial Highway; a marker honoring the 115th Infantry Regiment was completed in the median of US 15 in Emmitsburg in July 2006. 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.
Point of Rocks to Frederick US 15 enters Maryland at Point of Rocks, named for the pair of mountain peaks between which the Potomac River cuts through Catoctin Mountain in Maryland and Furnace Mountain in Loudoun County, Virginia. The highway crosses the river on the Point of Rocks Bridge, a two-lane, eight-span camelback truss bridge that also passes over the Chesapeake and Ohio Canal and CSX Transportation's Metropolitan Subdivision railroad line on the Maryland side of the river. Just north of the bridge, US 15 meets the western terminus of MD 28 (Clay Street), which serves as the main street of the community of Point of Rocks. The U.S. Highway heads north as a two-lane expressway that passes through a mix of farmland and forest on the eastern flank of Catoctin Mountain. North of its roundabout at MD 464 (Point of Rocks Road), US 15 has only two intersections, with Basford and Mountville roads, before becoming a two-lane freeway. The highway then passes Elmer Derr Road and reaches a partial interchange with US 340 (Jefferson National Pike) east of Jefferson. There is no direct access from northbound US 15 to westbound US 340 or from eastbound US 340 to southbound US 15; that access is provided by using the Mt. Zion Road interchange to get turned around.
US 15 and US 340 run concurrently northeast toward Frederick as a four-lane freeway. The two highways have a diamond interchange with Mt. Zion Road and cross over Ballenger Creek. The road has a diamond interchange with Jefferson Technology Parkway (MD 872G). On the southwest side of Frederick, the freeway has a partial interchange with I-70 (Eisenhower Memorial Highway), a folded diamond interchange with MD 180 (Jefferson Pike), and a partial cloverleaf interchange with the Frederick Freeway, which carries US 40 through the interchange. US 340's eastern terminus is within the third interchange, where US 15 exits north onto the Frederick Freeway and Jefferson Street continues east toward downtown Frederick.
US 15 continues north concurrent with US 40 along the six-lane Frederick Freeway. US 40 exits the freeway at a partial cloverleaf interchange with Patrick Street, which heads east toward downtown Frederick and west through the heavily commercialized Golden Mile. US 15 crosses Carroll Creek and continues north with four lanes through folded diamond interchanges with Rosemont Avenue, 7th Street, and Motter Avenue. All three streets provide access to Fort Detrick, home of the US Army Medical Research Institute of Infectious Diseases. In addition, Rosemont Avenue leads to Hood College and Motter Avenue connects the freeway with Frederick Community College. The route comes to partial interchange with the western terminus of MD 26 (Liberty Road) before the Frederick Freeway ends at a diamond interchange with Monocacy Boulevard/Christophers Crossing.
Frederick to Emmitsburg
US 15 continues north as a four-lane freeway through the Monocacy Boulevard/Christophers Crossing interchange, then becomes a four-lane expressway. Skirting the Frederick city limits, the highway crosses Tuscarora Creek and parallels the Monocacy River. It then has superstreet intersections with Willow and Biggs Ford roads. Just after passing the Frederick city limits, the highway has a superstreet intersection with Sundays Lane. Continuing north to the hamlet of Hansonville, the highway has an offset T-intersection with Old Frederick Road, followed by a superstreet intersection with Devilbiss Bridge Road/Bartgis Road. US 15 crosses Fishing Creek to the west of Lewistown and is closely paralleled on the west by Auburn Road as the highway gradually approaches the eastern flank of Catoctin Mountain. At the northern end of Auburn Road, MD 806 (Catoctin Furnace Road) begins to parallel the northbound side of the highway, which follows the eastern boundary of Cunningham Falls State Park just west of the village of Catoctin Furnace. Access to the main section of the state park is provided by Catoctin Hollow Road, which intersects the southbound lanes of US 15 and follows Little Hunting Creek up the mountain. The park's Manor Area is accessible from US 15 at an intersection a short distance north of Catoctin Hollow Road, which also provides further access to MD 806.
North of its intersection with Blue Mountain and Pryor roads, US 15 leaves the park boundary and the highway has a southbound exit ramp to Pryor Road. On the southern edge of the town of Thurmont, the 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 partial cloverleaf 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. The southbound lanes of the highway intersect Sandy Spring Lane (unsigned MD 15D) and US 15 crosses over the Maryland Midland Railway. At the north end of Thurmont, US 15 meets MD 550 (Church Street) at a diamond interchange before crossing Owens Creek, which MD 550 follows up the mountain as Sabillasville Road. The highway heads northeast through farmland and meets Motters Station Road (also the northern end of MD 76) at a superstreet intersection before bisecting the campus of Mount St. Mary's University. On campus, the highway has a superstreet intersection with Annandale Road/College Lane; Annandale Road serves the main part of the campus and the National Shrine Grotto of Our Lady of Lourdes to the west of the highway; College Lane serves the athletic complex, which includes Knott Arena, to the east of the highway.
North of Mount St. Mary's University, US 15 meets the southern end of US 15 Business (US 15 Bus.; South Seton Avenue) at a superstreet intersection that also serves Old Frederick Road; U-turn ramps on either side of the intersection provide the missing movements. The highway crosses Toms Creek and Flat Run along the eastern side of the town of Emmitsburg before its interchange with MD 140 (Main Street); MD 140 is accessed via a pair of right-in/right-out interchanges with Emmit Gardens Drive, which is unsigned MD 904H on the northbound side of US 15 and MD 904F on the southbound side. North of MD 140, the southbound side of US 15 has a welcome center, the Mason and Dixon Discovery Center; the northbound side of the highway can access the welcome center via a U-turn ramp. US 15's last intersection in Maryland is with the northern end of US 15 Bus. (North Seton Avenue) and Welty Road, which leads to Old Gettysburg Road; there is an unusual configuration on the southbound side: the right-out from northbound US 15 Bus. to southbound US 15 is about south of the turn-in to US 15 Bus.; there is also no direct access from northbound US 15 Bus. to northbound US 15. North of the intersection, US 15 becomes a four-lane freeway that continues across the Pennsylvania state line as the U.S. Highway's bypass of Gettysburg.
History
When the U.S. Numbered Highway System was laid out in 1926, US 15 did not enter Maryland. US 240 followed US 15's current corridor from Frederick north to near Harrisburg. No U.S. Highway connected Frederick and Leesburg via Point of Rocks. By the end of 1927, US 240 was reduced to a Washington–Frederick highway and US 15 connected Point of Rocks and Emmitsburg via Frederick as it does today.
Original construction and early improvements US 15 was established partially along what had been a pair of turnpikes. The Frederick and Emmitsburg Turnpike connected Emmitsburg with Harmony Grove which was located at the northern end of Market Street at MD 26 on the north side of Frederick. The Frederick and Buckeystown Turnpike ran from its co-terminus with the Frederick and Monocacy Turnpike at Evergreen Point at what is today the junction of MD 85 and MD 355, south to south of Buckeystown. When the Maryland State Roads Commission (MDSRC) designated highways to be improved as part of a state road system in 1909, the Frederick–Emmitsburg highway was included in the new system. The MDSRC originally planned to build the state road north from the city of Frederick along the Frederick and Turnpike, then turn east along Hayward Road to meet the Frederick and Emmitsburg Turnpike at Harmony Grove.