The George Washington Memorial Parkway, colloquially the G.W. Parkway, is a parkway that runs along the south bank of the Potomac River from Mount Vernon, Virginia, northwest to McLean, Virginia, and is maintained by the National Park Service (NPS). It is located almost entirely within Virginia, except for a short portion of the parkway northwest of the Arlington Memorial Bridge that passes over Columbia Island within the District of Columbia. The parkway is separated into two sections joined by Washington Street (State Route 400) in Alexandria. A third section, which is the Clara Barton Parkway, runs on the opposite side of the Potomac River in the District of Columbia and suburban Montgomery County, Maryland. A fourth section was originally proposed for Fort Washington, Maryland, but never built. The parkway has been designated an All-American Road. Virginia's official state designation for the parkway is State Route 90005. Route description Southern section At Mount Vernon, the parkway begins at a traffic circle, where it joins/leaves SR 235. Most of this route was taken from the Washington, Alexandria and Mount Vernon Railway's right-of-way. The southern section is a limited-access highway, but with at-grade intersections. It extends from Mount Vernon, past Fort Hunt to South Washington Street at the southern end of Alexandria. The Mount Vernon Trail parallels the southern and middle sections of the parkway (from Mount Vernon to Theodore Roosevelt Island), and is often filled with recreational and commuter cyclists and runners. Points of interest on or near the parkway are Mount Vernon Plantation, Huntley Meadows Park, P. O. Box 1142, Fort Hunt Park, Dyke Marsh, Hunting Creek, Jones Point, and the Woodrow Wilson Bridge. Although designated as part of the George Washington Memorial Parkway, Washington Street in Alexandria still belongs to and is maintained by the City of Alexandria. In 1929, the city and the federal government entered into a memorandum of agreement (MOA). The MOA gave the federal government a permanent and irrevocable easement over Washington Street. It also called for the construction of roundabouts at both the north and south ends of Washington Street as transition points between the rural and urban sections of the parkway. Finally, the MOA required Alexandria to adopt zoning regulations so that construction along Washington Street would be "of such character and of such types of buildings as will be in keeping with the dignity, purpose and memorial character of said highway". Commercial vehicles,