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 poplars. At one time Pennsylvania Avenue provided an unobstructed view between the White House and the Capitol. The construction of an expansion to the Treasury Building blocked this view, and supposedly President Andrew Jackson did this on purpose. Relations between the president and Congress were strained, and Jackson did not want to see the Capitol out his window, though in reality the Treasury Building was simply built on what was cheap government land. In an effort to tame dust and dirt, Pennsylvania Avenue was first paved using the macadam method in 1832, but over the years other pavement methods were