9/11 Remains the Deadliest Terrorist Attack in U.S. History
Washington, September 12, 2026: The September 11, 2001 terrorist attacks remain by far the deadliest terrorist incident in the history of the United States, with nearly 3,000 people killed in the coordinated attacks.
The attacks targeted the World Trade Center in New York, the Pentagon and a fourth aircraft that crashed in Pennsylvania after passengers attempted to regain control of the plane.
According to widely cited official figures, 2,996 people died in connection with the September 11 attacks, including the 19 hijackers.
A Death Toll Far Above Other Major Attacks
The scale of the September 11 tragedy stands apart from other high-profile acts of violence in the United States.
The Oklahoma City bombing in 1995 killed 168 people, while the 2016 attack at the Pulse nightclub in Orlando resulted in 49 victims being killed. The 2015 San Bernardino attack killed 14 people, and the 2017 New York City truck attack killed eight.
The 2017 Las Vegas mass shooting resulted in 60 victims being killed, although it is generally categorized as a mass shooting rather than an act of terrorism by U.S. authorities.
Because definitions and datasets differ, comparisons between terrorism, mass shootings and other forms of targeted violence must be made carefully.
The Extraordinary Impact of September 11
The September 11 attacks had consequences extending far beyond the immediate loss of life. They fundamentally changed U.S. national security policy and contributed to major changes in airport security, intelligence operations, counterterrorism programs and America’s foreign policy.
The attacks also led to the U.S.-led military campaign in Afghanistan and significantly influenced international counterterrorism cooperation.
More than two decades later, September 11 remains a defining event in modern American history. Its death toll and long-term political and security consequences distinguish it from virtually every other terrorist attack experienced by the United States.
The comparison also highlights why reliable definitions and consistent data are essential when examining terrorism and other forms of mass violence.
