14th Street NW/SW is a street in Northwest and Southwest quadrants of Washington, D.C., located 1.25 miles west of the U.S. Capitol. It runs from the 14th Street Bridge north to Eastern Avenue.
Northbound U.S. Route 1 runs along 14th Street from the bridge to Constitution Avenue, where it turns east with US 50. US 1 southbound previously used 15th Street NW due to the ban on left turns from westbound Constitution Avenue to 14th Street, but it now uses the Ninth Street Tunnel, five blocks to the east. 14th Street crosses the National Mall and runs near the White House and through the western side of Washington's Logan Circle neighborhood.
Because it connects to one of the main bridges crossing the Potomac River into Virginia, 14th Street has always been a major transportation corridor. It was the location of one of the first streetcar lines, and today it is the location of several afternoon carpooling "slug lines", which allow commuters to meet the high-occupancy vehicle requirements of I-395, the Henry G. Shirley Memorial Highway.