Pennsylvania Avenue lighthearted celebrations, including a series of day- and nighttime Shriner's parades in the 1920s and 1930s. Thomas and Concepcion Picciotto are the founders of the White House Peace Vigil, the longest running anti-nuclear peace vigil in the US, at Lafayette Square on the 1600 block of Pennsylvania Avenue. After the Oklahoma City bombing in 1995, the Secret Service closed the portion of Pennsylvania Avenue in front of the White House to all vehicular traffic. Pedestrian and bicycle traffic, however, was still permitted on the sidewalk. After 9/11 this policy was made permanent. Near the White House traffic is redirected to
Pennsylvania Avenue National Historic Site "the middle of the avenue from the president's palace to the capitol" cleared. The origin of the name "Pennsylvania Avenue" is somewhat obscure. The name was first applied to the avenue in a letter from surveyor and map-maker Benjamin Ellicott to the District's commissioners in December 1791. The actual clearing of Pennsylvania Avenue did not begin until spring 1796. Much of Pennsylvania Avenue below 9th Street was swampy and nearly unusable, as Tiber Creek curved north to border the avenue at 9th Street and again at 5th and 4th Streets before actually crossing it at 2nd Street. The damp earned