The two gaps in MD 117 were filled in the early to mid-1950s before the route between Boyds and Gaithersburg was transferred to county maintenance in the late 1950s.

The highway curves southeast at its tangent junction with Barnesville Road and assumes that name as it approaches the village of Boyds.

The highway intersects Metropolitan Grove Road, which leads to the eponymous MARC station.

The highway continues east as West Diamond Avenue along the northern edge of an unincorporated enclave within the city of Gaithersburg.

[1][2] East of the federal agency's campus, MD 117 has a partial interchange with I-270 (Eisenhower Memorial Highway).

Connections with I-270 in the direction of Frederick are made via the freeway's interchange with MD 124 to the north.

MD 117 drops to three lanes through the interchange, then expands to a four-lane divided highway again at Perry Parkway.

West Diamond Avenue continues east as a city street that parallels the Metropolitan Subdivision rail line under MD 355.

Songwriters Bill Danoff and Taffy Nivert, who later formed the Starland Vocal Band, wrote much of "Take Me Home, Country Roads" in December 1970 while working in Georgetown.

The song was inspired by a drive along Clopper Road to a family reunion in Gaithersburg.

Denver, Danoff, and Nivert first performed the song December 30, 1970, at The Cellar Door in Georgetown.

[10][7] A third section of macadam road was also built from the modern MD 117–MD 124 intersection west to the hamlet of Clopper east of Great Seneca Creek by 1933.

[15] However, in 1959, MD 117's eastern terminus was rolled back to the railroad crossing at Boyds.

[22] Since at least 1950, West Diamond Avenue had passed under MD 355's bridge across the railroad and met that highway at an oblique intersection.