Clara Barton Parkway begins at an intersection with MacArthur Boulevard in Carderock. MacArthur Boulevard heads west toward Great Falls and the affluent community of Potomac. Clara Barton Parkway heads east as a two-lane highway that expands to a four-lane divided highway ahead of its diamond interchange with an access road to the Carderock Division of the Naval Surface Warfare Center to the north, which features the David Taylor Model Basin, and Carderock Recreation Area of the Chesapeake and Ohio Canal to the south. East of the naval lab, the two roadways split for the parkway's six-ramp interchange with I-495. There is no direct access from westbound Clara Barton Parkway to northbound I-495 or from southbound I-495 to the eastbound parkway. The parkway roadways come together in Cabin John just west of parking areas accessible from the eastbound direction to C&O Canal Lock 10 and C&O Canal Lock 8 and River Center. Access to Cabin John is provided by a diamond interchange to a road connecting the parkway with MacArthur Boulevard in that community. Clara Barton Parkway reduces to one lane eastbound as it crosses Cabin John Creek and meets Cabin John Parkway at a partial interchange featuring ramps from westbound Clara Barton Parkway to northbound Cabin John Parkway and from Cabin John Parkway to eastbound Clara Barton Parkway, which becomes two lanes again. The parkway continues east to its final interchange, which provides access to MacArthur Boulevard in Glen Echo, the location of Glen Echo Park and Clara Barton National Historic Site. The interchange features a U-turn ramp from the eastbound direction to the westbound lanes of the parkway, a tight right-turn ramp from the access road to westbound Clara Barton Parkway, and an unused bridge over the westbound direction. There is no access from MacArthur Boulevard to the eastbound parkway. East of Glen Echo, Clara Barton Parkway reduces to a two-lane undivided highway that closely parallels MacArthur Boulevard on the hillside to the north. The parkway passes a pair of parking areas for Little Falls before temporarily expanding to a four-lane divided highway while passing a third parking area for C&O Canal Lock 6. Clara Barton Parkway crosses Little Falls Branch and enters the District of Columbia before reaching its eastern terminus at an intersection with Canal Road and Chain Bridge Road. Canal Road heads east toward Georgetown while Chain Bridge Road crosses the Chain Bridge into Arlington, Virginia to connect with Virginia State Routes 120 and 123. Commercial vehicles, including trucks, are prohibited from Clara Barton Parkway without a permit from the National Park Service, which maintains the highway. Speed limits on the parkway are from the western terminus to the Carderock interchange, from the Carderock interchange to the Glen Echo interchange, and from the Glen Echo interchange to the Chain Bridge. Clara Barton Parkway operates as a one-way road between the Glen Echo interchange and its eastern terminus at the Chain Bridge Monday to Friday. Traffic flows eastbound only toward Washington from 6:15 a.m. to 10 a.m. and westbound only toward Glen Echo from 2:45 p.m. to 7:15 p.m. Clara Barton Parkway is a part of the National Highway System as a principal arterial for its entire length.
History
Congress approved the construction of parkways on both sides of the Potomac River from Great Falls to Fort Washington and Mount Vernon in Maryland and Virginia, respectively, in 1930. Construction on what was originally named the George Washington Memorial Parkway on the Maryland side of the Potomac River was underway by 1961. The parkway was completed from its western end at MacArthur Boulevard to the interchange with Cabin John Parkway, which was not yet completed, in 1964. In 1965, the parkway opened from Cabin John east to the Glen Echo interchange. Extensions of the George Washington Memorial Parkway were proposed in both directions. From the west end, the parkway was to extend to the Chesapeake and Ohio Canal National Historical Park site at Great Falls. Going east, the parkway would continue to Georgetown, where it would tie into the western end of the Whitehurst Freeway at its junction with the Francis Scott Key Bridge. The unused bridge at the Glen Echo interchange was constructed and preliminary infrastructure work was done east of the interchange in anticipation of constructing a second carriageway east toward Georgetown. The plans to extend the parkway to Great Falls and Georgetown were abandoned by 1969. The parkway was completed in its present form from the Glen Echo interchange to the Chain Bridge in 1973. Maryland's version of the George Washington Memorial Parkway was renamed for Clara Barton in 1989.