Maryland Route 255 (MD 255) is a state highway in the U.S. state of Maryland. The highway runs 4.21 miles (6.78 km) from MD 2 near Owensville east to Riverside Drive in Galesville. MD 255, which was built in the 1920s, originally included the portion of MD 468 between Galesville and Shady Side; the section in Galesville was MD 393. MD 255 and MD 468 were assigned to their present courses in the late 1940s.