War on Terrorism (2001—)

September 11, 2001, ushered in a new age in America and in America's relations with the world. On that date, terrorists flew hijacked airliners into both of the World Trade Center towers, killing themselves, their fellow passengers, and several thousand people inside the buildings. Another hijacked plane was flown into the western face of the Pentagon—the Arlington, Virginia, headquarters of the U.S. military. Yet another crashed in a field near Shanksville, Pennsylvania, after its passengers, having heard of the earlier attacks at the Pentagon and World Trade Center, stormed their hijackers. This brave but Pyrrhic victory prevented an attack on another prominent American landmark—possibly the U.S. Capitol Building or the White House itself.

As America and the world watched on live television, both of the Trade Center's towers collapsed; many emergency workers and firefighters were killed along with those they had entered the buildings to rescue. The final death toll in New York was over 2,600, with the total number of people killed in the four attacks totaling around 3,000, including all passengers on the aircraft. This tally, while horrifically high, was—considering the fact that over 50,000 people worked at the World Trade Center on a typical day—also mercifully low. That said, the sheer scale and scope of these attacks dwarfed any previous terrorist strike.

Immediately after the attacks, America was a nation in mourning and a nation under siege; for the first time, air traffic was almost totally grounded for three days. The state of alert that followed the attacks in the United States was also mirrored overseas, with flights over London, for instance, barred for several days. The New York Stock exchange closed until September 17, and within a week of its reopening, the Dow Jones Industrial Index experienced its largest drop ever over such a short time period. America was effectively a nation at war, with its leaders vowing vengeance on those responsible for the most serious attack on the continental United States in almost 200 years, and its citizens demanding justice for an outrage they could barely believe had happened. The September 11 attacks impacted U.S. society at a fundamental level, and were viewed by many as not only an attack on America, but as an attack on the civilized world itself.

Onlookers watching the smoke and flames pouring from the World Trade Center in New York following terrorist attacks on September 11, 2001. (Associated Press/AP)