|Former name(s)||Conduit Road|
|Length||12.9 mi (20.8 km)|
|C&O Canal Scenic Byway|
|Restrictions||No commercial vehicles over 4 wheels or 6 tons in Maryland|
|West end||Chesapeake and Ohio Canal National Historical Park|
|Clara Barton Parkway in Potomac, MD|
MD 614 in Bethesda, MD
|East end||Foxhall Road in Washington, DC|
MacArthur Boulevard is a road in Montgomery County, Maryland and Washington, D.C. The road follows a northwest–southeast route from the Great Falls area of the Chesapeake and Ohio Canal National Historical Park in Potomac, Maryland, to Foxhall Road NW and 44th Street NW in the Foxhall neighborhood of Washington, D.C., near the Georgetown Reservoir. MacArthur Boulevard runs parallel to the Clara Barton Parkway and the C&O Canal for most of its route, passing through the Palisades area of the District. In Cabin John, traffic is reduced to a single alternating lane as it passes over the Union Arch Bridge, the longest span masonry arch bridge in the Western Hemisphere, and which also carries the Washington Aqueduct.
The road was originally named Conduit Road, as it was built atop the Washington Aqueduct. The aqueduct delivers water from the Potomac River to the Dalecarlia Reservoir, which is the primary source of drinking water in the District of Columbia.
The road was renamed for General Douglas MacArthur on March 5, 1942, when a local resident living off the road proposed the name change to his friend, Texas representative Luther Alexander Johnson, who sponsored the bill in Congress.
In 1975, a bike path, the MacArthur Boulevard Bike Trail, was built along MacArthur Boulevard from Berma Road to the south driveway for the Defense Mapping Agency Topographic Center (DMATC), a short distance from the District line. In 2013, the county began a project to rebuild the road and bikeway to make it safer and more pleasant. The project widened the existing road by four feet (1.2 m) to provide three-foot (0.91 m) bike lanes in each direction and rebuild the bikeway with a five-foot-wide (1.5 m) vegetative buffer. Segment 2, between I-495 and Oberlin Road, was completed in 2014. Segment 3, between Oberlin and DC is scheduled to begin in 2020. Segment 1 will rebuild the road and trail between I-495 and Berma Road.
|Maryland||Montgomery||Potomac||0.0||0.0||Chesapeake and Ohio Canal National Historical Park||Dead end near Great Falls|
Falls Road / C&O Canal Scenic Byway west
|Scenic byway continues west|
Clara Barton Parkway east / C&O Canal Scenic Byway east to I-495
|Western terminus of Clara Barton Parkway; scenic byway continues east|
Clara Barton Parkway to I-495 – Washington
|Access via Clara Barton Access Road|
|Cabin John Creek||6.6–|
|Union Arch Bridge|
|Glen Echo–Bethesda line||6.8||10.9||Wilson Lane (MD 188 east)||Western terminus of MD 188|
MD 614 north (Goldsboro Road)
|Traffic circle; southern terminus of MD 614|
Clara Barton Parkway west to I-495
|Signalized with pedestrian/bike crosswalk and non-turning west-bound lane|
|9.8||15.8||District of Columbia–Maryland border|
|District of Columbia||Washington||12.9||20.8||Foxhall Road NW / 44th Street NW – Downtown||Eastbound traffic can only access Foxhall Road south.|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|