In 1946, President Truman signed an amendment to the Capper-Crampton Act which, among other things, called for the Parkway to be extended into Maryland from the District Line to Marlboro Pike (then known as Marlboro Road). This extension, however, was carried out by the Maryland-National Capital Park and Planning Commission and was never part of the Parkway, nor did it ever extend past the Suitland Parkway.
