 Maryland Route 704 ( MD 704 ) is a state highway in the U.S. state of Maryland . Known as Martin Luther King Jr . Highway , the highway runs 6 @.@ 53 miles ( 10 @.@ 51 km ) from Eastern Avenue at the District of Columbia boundary in Seat Pleasant east to MD 450 in Lanham . MD 704 is a four- to six @-@ lane divided highway that connects the northern Prince George 's County communities of Seat Pleasant , Landover , Glenarden , and Lanham . The highway was constructed along the right of way of the abandoned Washington , Baltimore and Annapolis Electric Railway ( WB & A ) in the early 1940s . In the late 1950s and early 1960s , MD 704 served as a temporary routing of U.S. Route 50 ( US 50 ) while the U.S. Highway 's freeway was under construction from Washington to Lanham . The route was expanded to a divided highway between Seat Pleasant and US 50 in the late 1960s and early 1970s . MD 704 was completed as a divided highway when the portion east of US 50 was expanded in the late 1990s . 
