Bowen Road
MD 4 in Prince George's County was originally the Washington and Marlborough Turnpike, which exited the District of Columbia on Bowen Road, headed east to Forestville, south to Meadows, then east through Upper Marlboro to Hills Bridge on the Patuxent River. An unnamed road continued east to Solomons Island Road in Lothian. When the Maryland State Roads Commission was established in 1908, this route became one of the original state roads. In 1910, the highway was paved from the D.C. border to what is today District Heights, as well as from Hills Bridge to Waysons Corner, where MD 4 meets MD 408 today. Marlboro Pike from the D.C. line to Hills Bridge and Mt. Zion Road between Hills Bridge and Lothian was fully paved by 1927, which was the same year MD 4 was assigned to the two named roads. Southern Maryland Boulevard was built between Waysons Corner and MD 2 in Sunderland in 1929 and 1930, and was designated MD 416 by 1933.