Maryland Route 187 is a state highway in the U.S. state of Maryland. Known as Old Georgetown Road, the highway runs 5.32 miles (8.56 km) from MD 355 and MD 410 in Bethesda north to Executive Boulevard in North Bethesda. MD 187 is a four- to six-lane highway that runs parallel to MD 355 through suburban areas of southern Montgomery County. The highway was paved through Bethesda by 1910. The remainder of MD 187 was constructed in the mid- to late 1920s. The highway was relocated at its northern end and expanded to a divided highway over most of its length in the late 1960s. MD 187's interchanges with Interstate 270 (I-270) and I-495 were built in the late 1950s and early 1960s, respectively; the former interchange was reconstructed in the early 2000s. The northern terminus was cut back from MD 355 to Executive Boulevard in 2016.

Maryland Route 355 (MD 355) is a 36.75-mile (59.14 km) north–south road in western central Maryland in the United States. The southern terminus of the route is in Bethesda in Montgomery County, where Wisconsin Avenue meets the county's border with Washington, D.C. The northern terminus is just north of a bridge over Interstate 70 (I-70)/U.S. Route 40 (US 40) in the city of Frederick in Frederick County, where the road continues north as Market Street through Frederick towards MD 26.