The highway received its present designation in the mid-1960s when MD 4 was rerouted south into Calvert County.

MD 408 continues east as a two-lane undivided road through a mix of commercial development, residences, and farmland.

The highway veers northeast beyond its intersection with MD 259 (Greenock Road) and passes the historic home Quarter Place.

[3] The highway was constructed as a 14-foot-wide (4.3 m) gravel road between 1916 and 1919 and designated the eastern end of MD 4 in 1927.

The highway from Washington to Upper Marlboro was once a turnpike and, as of 1898, was the longest gravel road (12 miles (19 km)) in the state.

[11] The old turnpike from Meadows to the western limit of Upper Marlboro was reconstructed as a macadam road by 1915, the same year the highway from the eastern limit of Upper Marlboro to the Patuxent River was constructed as a 14-foot-wide (4.3 m) concrete road.

[7] MD 4's freeway bypass of Upper Marlboro was built from Ritchie–Marlboro Road east to the Patuxent River between 1959 and 1962.