What major event happened on September 11, 2001, in the United States?

Why This Matters

On September 11, 2001, terrorists attacked the United States in the deadliest act of terrorism on American soil. Nineteen hijackers took control of four commercial airplanes. Two planes were flown into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse. A third plane hit the Pentagon, the headquarters of the U.S. military, near Washington, D.C. A fourth plane crashed in a field in Shanksville, Pennsylvania, after passengers fought back against the hijackers.

Nearly 3,000 people were killed that day, including office workers, firefighters, police officers, and the passengers and crew on the four planes. People from more than 90 different countries were among the victims. The attacks were carried out by the terrorist group al-Qaeda, led by Osama bin Laden.

The events of September 11 changed the United States in many ways. The government created the Department of Homeland Security and passed the Patriot Act to strengthen national security. Airport security became much stricter. The U.S. launched a military operation in Afghanistan to fight al-Qaeda and the Taliban. The effects of that day continue to shape immigration policy, foreign policy, and security procedures across the country. As a citizenship applicant, understanding this event shows you are aware of a turning point that deeply affected the nation you are joining.

Key Facts

• Terrorists attacked the United States on September 11, 2001
• Four planes were hijacked: two hit the World Trade Center, one hit the Pentagon, and one crashed in Pennsylvania
• Nearly 3,000 people were killed in the attacks
• The attacks were carried out by the terrorist group al-Qaeda
• The event led to major changes in U.S. security, including the creation of the Department of Homeland Security

Common Mistakes

• Giving too many details when a simple answer works, saying "Terrorists attacked the United States" is a complete and correct answer
• Confusing the date, it was September 11, 2001, not 2002 or another year
• Naming only one location, while you do not need to list all sites, be aware that attacks happened in New York, Virginia, and Pennsylvania

Study Tip

The answer to this question is straightforward: "Terrorists attacked the United States." You do not need to explain how or name the locations. Keep your answer simple and clear. The date itself, September 11, often called 9/11, is one of the most well-known dates in recent American history.