Maryland Route 648 is a collection of state highways in the U.S. state of Maryland. These nine highways are current or former sections of the Baltimore–Annapolis Boulevard between Annapolis and Baltimore via Glen Burnie. There are five signed mainline segments of MD 648 through Arnold, Severna Park, Pasadena, Glen Burnie, Ferndale, and Pumphrey in northern Anne Arundel County; Baltimore Highlands in southern Baltimore County; and the independent city of Baltimore. MD 648 mainly serves local traffic along its meandering route, with long-distance traffic intended to use the parallel and straighter MD 2 south of Glen Burnie and freeway-grade Interstate 97 (I-97), I-695, and MD 295 between Glen Burnie and Baltimore.

Maryland Route 2 is the longest state highway in the U.S. state of Maryland. The 79.24-mile (127.52 km) route runs from Solomons Island in Calvert County north to an intersection with U.S. Route 1 /US 40 Truck in Baltimore. The route runs concurrent with MD 4 through much of Calvert County along a four-lane divided highway known as Solomons Island Road, passing through rural areas as well as the communities of Lusby, Port Republic, Prince Frederick, and Huntingtown. In Sunderland, MD 2 splits from MD 4 and continues north as two-lane undivided Solomons Island Road into Anne Arundel County, still passing through rural areas. Upon reaching Annapolis, the route runs concurrent with US 50/US 301 to the north of the city. Between Annapolis and Baltimore, MD 2 runs along the Governor Ritchie Highway, a multilane divided highway that heads through suburban areas, passing through Arnold, Severna Park, Pasadena, Glen Burnie, and Brooklyn Park. In Baltimore, the route heads north on city streets and passes through the downtown area of the city.