List of White House security breaches

[1] Until the late 19th century, the White House maintained an open door policy with the public having access to the corridors and lobbies of the building.

This became a significant problem by the time of the Lincoln administration, which saw the building regularly filled with people "on all conceivable errands, for all imaginable purposes."

While Lincoln was, to begin with, adamant about the importance of speaking to regular people, it grew excessive and the White House began to restrict visiting hours for the public to a twice weekly slot.

[3] After World War II, public access to the White House grounds became increasingly restricted, with the visitor office providing scheduled tours to a limited area of the building.

During the mid-1990s, the fence was expanded by one block to move traffic farther from the White House to prevent damage from any car bomb.