Maryland Route 27 (MD 27) is a state highway in the U.S. state of Maryland. Known for most of its length as Ridge Road, the highway runs from MD 355 in Germantown north to MD 30 in Manchester. MD 27 follows a ridge that separates several watersheds in northern Montgomery County and Carroll County. The highway connects Germantown and Manchester with Damascus in far northern Montgomery County; Westminster, the county seat of Carroll County; and Mount Airy, which lies at the junction of Carroll, Frederick, Howard, and Montgomery counties and where MD 27 intersects Interstate 70 (I-70)/U.S. Route 40 (US 40).
MD 27 follows what was originally MD 29 and part of MD 31. The highway received its present number south of Westminster in a swap with US 29 in 1934 and north of Westminster in 1967. Ridge Road south of Mount Airy and Manchester Road between Westminster and Manchester was constructed as one of the original state roads in the early to mid-1910s. The Mount Airy– Westminster portion of MD 27 was built in the 1920s. MD 27 was reconstructed in the early to mid-1950s from Germantown to Westminster. MD 31 was reconstructed north of Westminster in the late 1950s; old segments of the highway became part of MD 852. MD 27 bypassed Mount Airy in the 1970s, leaving behind MD 808. The highway was relocated at its southern end in the mid-1990s to improve access between Damascus and Germantown and I-270.
Route description
MD 27 runs on top of or in the vicinity of a long ridge known for most of its length as Parr's Ridge. This ridge separates several sets of watersheds in central Maryland, with the result that MD 27 bridges no significant streams. From Germantown to south of Damascus, the ridge separates the waters of Little Seneca Creek to the west and Great Seneca Creek to the east; these creeks come together at Dawsonville and flow into the Potomac River. From Damascus north, all streams west of the ridge flow into the Monocacy River, including Bennett Creek, Bush Creek, and Little and Big Pipe Creek from south to north. All east-side streams flow into the Patuxent River from Damascus to the south of Mount Airy, the South Branch of the Patapsco River from Mount Airy to Taylorsville, and the Patapsco River North Branch from Taylorsville to Manchester. MD 27 is part of the National Highway System as a principal arterial in five sections: from MD 355 in Germantown to Gue Road in Damascus; from Penn Shop Road south of Mount Airy to the Frederick– Carroll county line; from I-70 to the northern town limit of Mount Airy; from Chapel Road south of Westminster to Old Manchester Road in Mexico; and from the southern town limit of Manchester to MD 30.
Germantown to Mount Airy
MD 27 begins as Ridge Road at an intersection with MD 355 (Frederick Road) on the northern edge of Germantown. Ridge Road continues west as a six-lane divided county highway to a partial cloverleaf interchange with I-270 (Eisenhower Memorial Highway), beyond which the county highway continues as Father Hurley Boulevard, one of the primary arteries of Germantown. MD 27 curves north through a directional intersection with Henderson Corner Road and reduces from a six-lane divided highway to a two-lane undivided road past its intersection with Brink Road. The highway passes through the hamlet of Cedar Grove on its way to Damascus. West of Damascus High School, MD 27 gains a center left-turn lane, a second lane northbound, then becomes a four-lane undivided highway. The highway becomes two lanes again at the west end of downtown Damascus, curves east then turn north to remain on Ridge Road. The road continues straight east as MD 108 (Main Street), which leads to MD 124 (Woodfield Road).
MD 27 starts of Damascus as a four-lane undivided highway but quickly drops to two lanes. At the north end of the unincorporated town, the state highway meets the northern end of county-maintained Woodfield Road. MD 27 meets the eastern end of MD 80 (Kemptown Road) in the hamlet of Claggettsville. The highway crosses the Patuxent River just south of its source and passes through the western edge of Howard County. Between a pair of intersections with Penn Shop Road, MD 27 crosses a sliver of Montgomery County before entering Frederick County and expanding to a four-lane divided highway. The highway meets the west end of the Mount Airy–Ellicott City segment of MD 144 (Old National Pike). The intersection is just west of Parrs Spring, the source of the South Branch of the Patapsco River. Parrs Spring contains the quadripoint where the boundaries of Montgomery, Howard, Frederick, and Carroll counties meet.