On September 11, 2001 four hijacked planes struck New York, Washington, and Pennsylvania, killing nearly 3,000 people.
The FBI launched its largest investigation in history, codenamed PENTTBOM.
Within weeks, U.S. authorities identified al-Qaeda and its leader, Osama bin Laden, as responsible, with the group having operated out of Afghanistan under the protection of the Taliban.
Twenty-four years ago, four hijacked planes struck New York, Washington, and Pennsylvania, killing nearly 3,000 people. While the immediate aftermath brought dramatic scenes, less visible changes soon transformed American life: sweeping security laws reshaped airports and public spaces, wars overseas redefined U.S. foreign policy, and national identity evolved amidst new debates about freedom, security, and civil liberties. The attacks also left lasting health, environmental, and social consequences, while annual commemorations and a rebuilt World Trade Centre keep the memory alive for a generation that knows 9/11 only as history.
What Happened on September 11, 2001?
In the early hours of that day, four commercial planes were seized shortly after take-off from airports in the northeastern United States. The first, American Airlines Flight 11, struck the North Tower of New York’s World Trade Centre at 8:46 a.m. Seventeen minutes later, United Airlines Flight 175 hit the South Tower. At 9:37 a.m., American Airlines Flight 77 crashed into the Pentagon outside Washington, while United Airlines Flight 93 came down in rural Pennsylvania after passengers attempted to wrest control from the hijackers. By 10:28 a.m., the Twin Towers, also known as the World Trade Centre, had collapsed, leaving behind devastation on an almost unimaginable scale. In total, nearly 3,000 people were killed that morning.
The immediate aftermath saw rescue operations begin simultaneously in lower Manhattan, at the Pentagon, and in Pennsylvania. First responders searched the rubble for survivors, though few were found, while hospitals prepared for mass casualties that never arrived. Air traffic across the United States was halted, with the Federal Aviation Administration grounding all civilian flights, and the New York Stock Exchange suspended trading until September 17. Families of the missing gathered near Ground Zero, taping photographs of loved ones to walls and fences, while BBC reporting at the time described New York as a city blanketed in ash and silence, its streets filled with crowds walking north on foot, away from lower Manhattan.
While these rescue and stabilization efforts unfolded, the FBI launched its largest investigation in history, codenamed PENTTBOM, and pursued hundreds of thousands of leads. Within weeks, U.S. authorities identified al-Qaeda and its leader, Osama bin Laden, as responsible, with the group having operated out of Afghanistan under the protection of the Taliban.
In parallel with investigative efforts, President George W. Bush addressed the nation from Washington, stating that the country had been targeted due to its freedoms and vowing to bring those responsible to justice. Congress soon authorised the use of military force against those who had planned or supported the attacks, setting the stage for U.S. intervention abroad. Subsequently, on October 7, U.S. and allied forces began bombing Afghanistan in an effort to remove the Taliban and dismantle al-Qaeda’s network.
At home, sweeping policy changes followed. The USA PATRIOT Act, signed on October 26, 2001, expanded surveillance and detention powers. In November, the newly created Transportation Security Administration began reshaping airport screening, while the Department of Homeland Security, established in late 2002 and operational by March 2003, consolidated multiple agencies under one umbrella. Leaders argued these measures were necessary to prevent further attacks, though civil liberties groups warned of government overreach.
Two Decades On
The consequences of September 11 extended far beyond that morning. The U.S. war in Afghanistan lasted two decades, ending only in 2021 with the withdrawal of American forces and the Taliban’s return to power. Reuters has noted that it became the longest war in U.S. history, costing the lives of thousands of American and allied troops and many times more Afghan civilians. The U.S.-led invasion of Iraq in 2003, justified in part through counterterrorism arguments, reshaped the Middle East and provoked lasting debates about American foreign policy.
Inside the United States, daily life was permanently altered. Airport security underwent a transformation, with body scans, identity checks, liquid restrictions, and the now-familiar removal of shoes becoming routine. Surveillance programs expanded, granting new powers to intelligence agencies. The phrase “homeland security,” rarely heard before, entered everyday language, while Muslim, Arab, and South Asian communities across the country reported harassment and profiling, especially in the years immediately after the attacks.
The health and environmental toll was also profound. Dust and toxins released by the collapse of the Twin Towers caused chronic illnesses among first responders, construction workers, and residents, leading the government to establish federal compensation funds. Forensic work to identify remains continued for years, with advances in DNA technology gradually returning names to fragments recovered from the rubble.
Commemoration became a central feature of public life. Each year, ceremonies are held at Ground Zero in New York, at the Pentagon, and in Shanksville, Pennsylvania. The names of the dead are read aloud, moments of silence mark the times when planes struck and when the towers fell, and bells are rung as family members gather with photographs of their loved ones. Leaders often take part; in 2021, President Joe Biden observed the 20th anniversary by visiting all three attack sites in a single day.
The rebuilt World Trade Center site now features the 9/11 Memorial and Museum. Opened in 2014, they include two reflecting pools situated in the footprints of the fallen towers. One World Trade Center, completed in 2013 and now the tallest building in the Western Hemisphere, stands nearby. For many families, the site remains both a place of mourning and of unresolved questions about accountability and legacy.
Internationally, the attacks triggered shifts in alliances and security practices. NATO invoked Article five, its collective defence clause, for the first and only time in its history. From Europe to Asia, governments introduced counterterrorism laws, tightened border controls, and strengthened intelligence cooperation. Critics, including human rights organisations, have argued that such measures blurred the line between security and individual rights, often at the expense of minorities and migrants.
As time has passed, historians and journalists have described September 11 as a pivotal moment; a point after which the 21st century took on a different shape. On the 20th anniversary, the BBC noted that for many younger Americans, the events are no longer a living memory but a part of history, taught in classrooms and memorialised in museums. Yet the consequences remain visible; in the wars that followed, in the security measures woven into daily routines, and in the politics of both fear and resilience.
