Known as Connecticut Avenue, the state highway runs 8.30 mi (13.36 km) from Chevy Chase Circle at the Washington, D.C., border north to MD 97 in Aspen Hill.

MD 185 serves as a major north-south commuter route in southern Montgomery County, connecting the District of Columbia with the residential suburbs of Chevy Chase, Kensington, and Wheaton.

The portion south of Kensington was included in the state highway system by 1927 as an extension of Connecticut Avenue out of the District of Columbia and was the westernmost stretch of MD 193.

[2] MD 185 heads north as a six-lane divided highway through an affluent residential area in Chevy Chase Village.

[1][2] MD 185 enters a commercial area where it run under bridges carrying the future Purple Line and the new alignment of the Capital Crescent Trail.

[2] After crossing Jones Bridge Road, MD 185 continues north through residential areas and intersects Interstate 495 (Capital Beltway) at a partial cloverleaf interchange.

[2] After leaving the town limits of Kensington, MD 185 becomes a six-lane divided highway with partial control of access, passing between residential subdivisions.

Connecticut Avenue continues as a county-maintained highway north across Bel Pre Road into Rossmoor, home of the Leisure World retirement community.

[1][3] The roadway that would become MD 185 was initially laid down in 1890 as an extension of Connecticut Avenue NW in Washington, D.C., by the Chevy Chase Land Company, a developer that had bought up some 1,700 acres in southern Montgomery County and Northwest D.C. with plans to create a streetcar suburb.

The first section to be built was between Chevy Chase and Kensington as an extension of Connecticut Avenue into Montgomery County, which was designated MD 193.