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 H Street or Constitution Avenue, both of which eventually link back with Pennsylvania Avenue. Plans drafted by District officials after the September 11th attacks call for Pennsylvania Avenue downtown to be used as a dividing line for any mass evacuation of the city. People north of the avenue would be directed north while those south of the avenue would be directed south. No vehicles would be allowed to cross the avenue. In 2002, the National Capital Planning Commission invited several prominent landscape architects to submit proposals for the redesign of Pennsylvania Avenue at the White House, with the intention that