Shortly before nine o'clock on the clear morning of September 11, 2001, the most devastating terrorist attack in American history began unfolding above the skies of the northeastern United States. Nineteen men affiliated with the Islamic extremist organization al-Qaeda hijacked four commercial airliners and turned them into weapons, killing 2,977 people and fundamentally reshaping the geopolitical landscape of the twenty-first century.
The plot had been years in the making. Al-Qaeda, led by the Saudi-born militant Osama bin Laden and operating primarily out of Afghanistan under the protection of the Taliban government, had carried out smaller attacks against American targets throughout the 1990s, including the bombings of U.S. embassies in Kenya and Tanzania in 1998 and an attack on the USS Cole in Yemen in 2000. The organization's stated grievances included American military presence in Saudi Arabia, U.S. support for Israel, and sanctions imposed on Iraq. The September 11 operation, however, was designed to strike at the symbolic heart of American power in a way that none of the previous attacks had approached.
Ringleader Mohamed Atta, an Egyptian-born engineer, commanded the first plane, American Airlines Flight 11, a Boeing 767 that had departed Boston's Logan Airport bound for Los Angeles. At 8:46 in the morning, Atta flew the aircraft directly into the North Tower of the World Trade Center in lower Manhattan. The impact tore a massive gash through the upper floors of the 110-story building, trapping hundreds of people above the point of impact and sending a fireball visible from miles away across the New York skyline.
Seventeen minutes later, at 9:03 a.m., hijacker Marwan al-Shehhi flew United Airlines Flight 175, also departing from Boston, into the South Tower of the World Trade Center. By this point, the world was watching. Television cameras already trained on the burning North Tower captured the second impact live, transforming what some had initially assumed might be a catastrophic accident into the unmistakable signature of a coordinated terrorist attack.
Meanwhile, a third group of hijackers had taken control of American Airlines Flight 77, which had taken off from Dulles International Airport in Virginia. At 9:37 a.m., hijacker Hani Hanjour flew the Boeing 757 into the western facade of the Pentagon, the headquarters of the United States Department of Defense in Arlington County, Virginia, causing a partial collapse of the building and killing 184 people inside and on the plane. A fourth aircraft, United Airlines Flight 93, departing from Newark bound for San Francisco, was seized by a fourth team of hijackers led by Ziad Jarrah. The intended target was believed to be either the United States Capitol or the White House in Washington, D.C. However, passengers aboard Flight 93 had learned through phone calls to relatives on the ground about the attacks in New York and at the Pentagon. In an act of extraordinary courage, they organized a revolt against the hijackers. At 10:03 a.m., the aircraft crashed into a field near Shanksville, Pennsylvania, killing all 44 people aboard but sparing whatever target had been chosen.
The physical consequences in New York were catastrophic. The South Tower collapsed at 9:59 a.m., less than an hour after impact. The North Tower followed at 10:28 a.m. The force of their collapse destroyed the remaining five structures in the World Trade Center complex. A total of 2,977 people perished in the attacks, including 343 firefighters and 72 law enforcement officers who had rushed into the towers to evacuate civilians. These casualties made September 11 the deadliest incident in American history for both firefighters and law enforcement personnel. The crashes of Flight 11 and Flight 175 into the towers constituted the deadliest aviation disasters in history. The Federal Aviation Administration ordered a complete ground stop across all U.S. airspace, requiring every airborne aircraft to land at the nearest available airport. Hundreds of international flights diverted to Canada under a coordinated effort known as Operation Yellow Ribbon.
That evening, the Central Intelligence Agency briefed President George W. Bush that its Counterterrorism Center had confirmed the attacks were carried out by al-Qaeda. The Bush administration's response was swift and far-reaching. Within weeks, the United States and allied forces invaded Afghanistan to dismantle al-Qaeda's infrastructure and remove the Taliban regime. NATO invoked Article 5 of its founding treaty for the first and only time in the alliance's history, treating the attack on the United States as an attack on all member nations. Despite these efforts, bin Laden himself eluded capture for nearly a decade, publicly denying involvement in the attacks until 2004 before eventually acknowledging responsibility on a recorded statement. He was finally killed during a U.S. Navy SEAL raid on his compound in Abbottabad, Pakistan, in May 2011.
The attacks caused at least ten billion dollars in immediate infrastructure and property damage, seriously harmed the U.S. economy, and sent shockwaves through global financial markets. In the years following, Congress passed sweeping new legislation expanding the surveillance and intelligence-gathering powers of federal agencies. The United States launched its broader global war on terror, eventually invading Iraq in 2003. The Costs of War Project at Brown University estimates that when the deaths caused by the conflicts directly triggered by the September 11 attacks are combined with the toll of the attacks themselves, the total number of fatalities exceeds 4.5 million people.
Cleanup of the World Trade Center site, known as Ground Zero, was completed in May 2002. The rebuilt One World Trade Center now stands as the tallest building in the Western Hemisphere. The National September 11 Memorial and Museum opened on the footprints of the original towers in 2011 and 2014 respectively, preserving the memory of those lost and documenting the events of that morning in exhaustive detail. Annual commemorations draw thousands of survivors, family members, and public officials to the site each year on the anniversary of the attacks.
September 11 remains a defining rupture in modern American and world history, the moment when the vulnerabilities of an interconnected, open society were exposed with lethal force, and the consequences of which continued to shape foreign policy, civil liberties debates, and international relations for decades afterward.
