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 Pennsylvania Avenue. This precedent was exercised 12 years later. On August 7, 1925, about 40,000 members of the Ku Klux Klan marched on Pennsylvania Avenue. The Klan repeated its march with a similar number of participants in 1926. The marches signified the height of the Klan's power in the United States, even as it was about to lose much of its strength. Another major demonstration on the avenue led to tragedy. In June 1932, thousands of homeless World War I veterans, their families, and their supporters occupied the recently condemned assemblage of buildings at the Federal Triangle construction site between