For many of today's citizens, Sept. 11, 2001, likely has replaced Dec. 7, 1941, as the "date which will live in infamy."
President Franklin D. Roosevelt used the phrase to describe the Japanese surprise attack on the Pearl Harbor Naval Station in Hawaii, leading directly to the United States' entry into World War II.
Ten years ago, the targets included government, military and civilian buildings, using civilian airplanes as the weapons - and most of the 2,976 people killed were civilians.
For many, including those who worked in or visited state office buildings in Missouri and other states, security grew tighter within weeks.
Metal detectors and searches of purses, briefcases and computer cases became a routine way of life - although they disappeared from Missouri government buildings several years later, when the state began experiencing budget shortfalls that came, in part, because the Sept. 11 attacks spurred an economic downturn.