Maryland Route 337 (MD 337) is a state highway in the U.S. state of Maryland. Known for most of its length as Allentown Road, the highway runs 3.41 miles (5.49 km) from MD 5 in Camp Springs east to MD 4 near Forestville. MD 337 runs along the southern end of Morningside and the northern edge of Andrews Air Force Base and provides access to several entrances to the military base. The state highway runs concurrently with the easternmost portion of Suitland Parkway. The parkway stretch of MD 337 is maintained by the National Park Service (NPS) instead of the Maryland State Highway Administration (MDSHA). MD 337 was constructed in the mid- to late 1910s along a course further south than the modern highway. The highway was moved to its present alignment to make way for the construction of Andre