U.S. Route 240 is a defunct designation for a short, but once very important, segment of highway between Frederick, Maryland, and Washington, D.C. It is now commonly known as Wisconsin Avenue, Maryland Route 355 (MD 355), and Interstate 270 (I-270). Route description This route description features US 240 as it existed in 1945, with references to today's highways to provide context. Washington, D.C. US 240 began at the intersection of Pennsylvania Avenue and 14th Street, NW, near the White House in Washington. US 240 headed west on Pennsylvania Avenue to 15th Street, then headed west from that intersection on Treasury Place for one block (entering an area now closed to the public and known as President's Park). The U.S. Highway curved around the south side of the South Lawn (White House) on South Executive Avenue past the Zero Milestone Marker to continue onto E Street west one block to 17th Street. US 240 followed 17th Street north to Farragut Square, where the highway intersected K Street, which carried US 50. US 240 continued north along Connecticut Avenue to Dupont Circle, which did not have an underpass for Connecticut Avenue when US 240 was designated. At the circle, the U.S. Highway met US 29, which used New Hampshire Avenue on both sides of the circle, and US 240 Alternate, which headed north on Connecticut Avenue. US 240 continued northwest on Massachusetts Avenue. The highway passed through Sheridan Circle, crossed Rock Creek on what is now named the Charles C. Glover Memorial Bridge, and passed along part of Observatory Circle on the edge of the circular U.S. Naval Observatory grounds. US 240 followed Massachusetts Avenue to its intersection with Wisconsin Avenue next to Washington National Cathedral. There, the U.S. Highway turned north and followed Wisconsin Avenue through Tenleytown to the District of Columbia boundary at Western Avenue in Friendship Heights. By 1959, the starting point and routing of US 240 south of Massachusetts Avenue and 22nd Street (one block east of Sheridan Circle) had changed. The southern terminus was at the traffic circle around the Lincoln Memorial (which carried US 50) heading north on 23rd Street, NW, passing through Washington Circle where it intersected with US 29 which headed west on K St. and northeast on New Hampshire Avenue. Due to one-way roads the north and southbound lanes of US 240 ran on different streets for the next six blocks. Northbound US