September 11 Attacks
Al-Qaeda terrorists hijacked four commercial aircraft and killed nearly 3,000 Americans in simultaneous attacks on the World Trade Center and Pentagon — transforming American security policy, civil liberties, and foreign policy.
What Happened
On September 11, 2001, al-Qaeda operatives hijacked four commercial aircraft. Two planes struck the Twin Towers of the World Trade Center in New York City, causing both towers to collapse. One struck the Pentagon in Arlington, Virginia. The fourth crashed near Shanksville, Pennsylvania after passengers overpowered the hijackers. 2,977 people died. In the aftermath, President Bush signed the PATRIOT Act, the Department of Homeland Security was created, and the United States invaded Afghanistan within weeks. The attacks launched the 'War on Terror' — a decadeslong military and security campaign that reshaped American foreign policy, domestic surveillance, and civil liberties.
Why It Mattered Then
September 11 was the deadliest foreign attack on American soil in history. It produced a national unity and will for action that allowed sweeping changes to law, policy, and government organization.
Why It Matters Now
9/11 fundamentally changed American security culture, civil liberties law, and foreign policy. Its legacy includes the wars in Afghanistan and Iraq, expansion of domestic surveillance, the TSA, FISA courts, Guantanamo Bay, and ongoing debates about balancing security and freedom.
Key Themes
This event is part of the 2001–2026: Security, Digital Life, AI, and America at 250 era (2001–2026).
Explore This Era →