GEORGE WASHINGTON PARKWAY From: Mount Vernon To: at the American Legion Bridge NOTE: Within the city limits of Alexandria this is
Washington St. and not under the National Park Service Total Length: 23.5 miles
Creation: The George Washington Parkway started out in 1932 as the Mount Vernon Memorial Blvd., running from VA 710-725 (curr VA 235) Mt. Vernon to US 1 (curr I-395, US 1) at the 14th St. Bridge, with the Washington St. split in place.
Adjustments: In 1952, the GW Pkwy was extended north to end at US 29-211 (curr US 29-VA 124 jct).
Between 1954-55, VA 124 was born, shortening this extension by 3/4 mile.
In 1960-61, GW Pkwy was extended north to VA 123. The segment that cut west from the river to VA 124 became Spout Run Parkway.
In 1962, the Parkway was given its current routing up to I-495.
In 2003, VA 90005 was assigned to the entirety of the George Washington Parkway for administrative purposes. Note that VA 90005 is also assigned to the Washington St. portion through Alexandria, and is a useless multiplex with VA 400 (shown this way on VDOT traffic count reports).
Posting: No specific shield for the GW Pkwy exists. It is well identified from I-495 and the interchanges near Washington DC. It is not marked at all at VA 235, you have to use the roundabout at the Mt. Vernon Visitor Center to reach the Parkway, but no signs tell you this.
Comments: The GW Parkway follows the Potomac River for its entire length. North of I-66, the road climbs well above the river level. This is the most scenic ride in Northern Virginia, although it is a heavily used commuter route. Accidents in the last several years prompted the Park Service to erect median barriers.
It is an unsigned fact that the GW Parkway crosses into Washington DC when it crosses Columbia Island near the Memorial Bridge. The interchange around the Memorial Bridge-VA 27-US 50 is very complex and hard to negotiate if you are unfamiliar with where all the ramps go.
Other than access to Theodore Roosevelt Island, the Parkway HQ, and LBJ grove, the parkway uses only interchanges north of I-395, though it blows off VA 120. South of I-395 there are at-grade intersections all the way to Mt. Vernon.
The GW Parkway is the main access route to Reagan National Airport.
The GW Parkway has been 4-lane for at least 60 years.
Mount Vernon 
at the American Legion Bridge
Washington St. and not under the National Park Service