Maryland Route 121

Maryland Route 121
Clarksburg Road
Maryland Route 121 highlighted in red
Route information
Maintained by MDSHA
Length:	3.96 mi (6.37 km)
Existed:	1927 – present
Major junctions
South end:	MD 117 in Boyds
	I-270 in Clarksburg
North end:	Stringtown Road in Clarksburg
Location
Counties:	Montgomery
Highway system
Maryland highway system Interstate US State Scenic Byways ← MD 119 MD 122 →

Maryland Route 121 (MD 121) is a state highway in the U.S. state of Maryland. Known as Clarksburg Road, the highway runs 3.96 miles (6.37 km) from MD 117 in Boyds north to Stringtown Road between Interstate 270 (I-270) and MD 355 in Clarksburg. MD 121 connects Boyds and Clarksburg in northern Montgomery County. The highway was paved from Clarksburg to Boyds in the early to mid-1910s. MD 121 was extended to north of Clarksburg in the late 1920s and early 1930s. MD 121 was relocated through Clarksburg in the mid-1950s when I-270 was constructed through the area. The highway's northern end was rolled back to MD 355 in the mid-1970s. MD 121 was relocated in Boyds in the mid-1980s. The highway's northern end was moved to its present terminus just north of I-270 when Stringtown Road was constructed in the mid-2000s. In addition to the Boyds–Clarksburg route, MD 121 has also included three disjoint segments in Dawsonville and Germantown. All three of these routes were segments of the original MD 119.

MD 121 begins at a T intersection with MD 117 in the village of Boyds. MD 117 heads west along Barnesville Road and south along a continuation of Clarksburg Road, which passes under CSX's Metropolitan Subdivision next to the Boyds station on MARC's Brunswick Line. MD 121 heads north as a two-lane road that crosses the Tenmile Creek branch of Little Seneca Lake. The highway passes through the hamlet of Burdette and intersects Old Baltimore Road, which provides access to Black Hill Regional Park to the east. On the southern edge of the developed area of Clarksburg, MD 121 has a four-ramp partial cloverleaf interchange with I-270 (Eisenhower Memorial Highway). Just north of the route's bridge across of the freeway, the highway expands to a four-lane divided highway and reaches its northern terminus where the ramp from northbound I-270 merges onto northbound MD 121. The divided highway continues as Stringtown Road, a county highway that serves as one of the main streets through the developed part of Clarksburg and intersects MD 355 (Frederick Road).