September 11th, 2001 – This Day in History

September 11, 2001, began as an ordinary Tuesday in the United States and became the deadliest terrorist attack in history. Nineteen al-Qaeda hijackers seized four U.S. commercial airliners, turning them into weapons against high-profile civilian and military targets. American Airlines Flight 11 and United Airlines Flight 175 were flown into the World Trade Center’s North and South Towers at 8:46 a.m. and 9:03 a.m. Eastern Time, igniting infernos that led to both towers’ catastrophic collapse. At 9:37 a.m., American Airlines Flight 77 struck the Pentagon. The fourth aircraft, United Airlines Flight 93, crashed at 10:03 a.m. in a field near Shanksville, Pennsylvania, after passengers and crew mounted a sustained revolt upon learning of the other attacks. Investigators later concluded that the hijackers intended to hit either the U.S. Capitol or the White House.

In all, 2,977 victims were killed that morning—office workers, airline passengers and crew, military and civilian personnel at the Pentagon, and first responders who rushed into danger. The death toll included 343 firefighters and 72 law-enforcement officers, the largest single-day loss for both groups in U.S. history. Thousands more were injured, and many survivors and responders would later suffer long-term health effects linked to toxic exposures. The 19 hijackers also died in the attacks.

The shock of 9/11 reverberated globally. In the United States, it triggered immediate emergency responses, the largest mobilization of search and rescue in New York City’s history, and a months-long recovery operation at the World Trade Center site. Policy responses reshaped national security and everyday life: Congress passed the Authorization for Use of Military Force, and the U.S. launched military operations in Afghanistan to dismantle al-Qaeda and remove the Taliban regime that harbored it. Domestically, the government created the Department of Homeland Security, strengthened intelligence coordination, and overhauled aviation security—most visibly through the formation of the Transportation Security Administration and new screening protocols.

The attacks also had profound economic and cultural effects. Markets were disrupted, air travel halted, and lower Manhattan’s infrastructure suffered extensive damage. Memorialization efforts began alongside recovery: across the country, communities established vigils, service traditions, and local memorials to honor those killed. At the World Trade Center site, the 9/11 Memorial and, later, the 9/11 Memorial Museum were dedicated to preserving the names, stories, and artifacts of the day. Ongoing forensic work has continued to identify victims’ remains, underscoring the attacks’ enduring human dimension even decades later.

More than two decades on, September 11 stands as a defining moment—one of collective grief, bravery, and transformation—shaping policy, remembrance, and civic life in the United States and around the world.

We will never forget…