What major event took place on September 11, 2001, in the U.S.?

The events of September 11, 2001, are significant in U.S. history as they marked a day of unprecedented terror and tragedy. On this day, al-Qaeda terrorists hijacked four commercial airplanes, using two of them to strike the Twin Towers of the World Trade Center in New York City and a third to hit the Pentagon in Arlington, Virginia. The fourth plane, United Airlines Flight 93, was headed for another target in Washington, D.C., but passengers attempted to regain control, resulting in its crash in Pennsylvania.

These coordinated attacks killed nearly 3,000 people and instigated widespread fear and global condemnation. The aftermath saw a significant shift in U.S. domestic and foreign policy, including the initiation of the War on Terror, the wars in Afghanistan and Iraq, and the formation of the Department of Homeland Security. The September 11 attacks are a pivotal moment in U.S. history that reshaped national security and international relations for years to come.