Twenty-five years ago today, the United States suffered the deadliest terrorist attack in its history.
On September 11, 2001, 19 al-Qaeda terrorists hijacked four commercial airplanes and turned them into weapons. Two struck the World Trade Center in New York City, one hit the Pentagon outside Washington, and a fourth crashed in a field near Shanksville, Pennsylvania, after passengers and crew fought back against the hijackers.
In all, 2,977 victims were killed. Thousands more were injured, and the effects of that morning continued long after the fires were extinguished. First responders, recovery workers and others exposed to toxic dust and debris later developed serious illnesses, adding another painful chapter to the legacy of the attacks.
For Americans old enough to remember September 11, the day remains difficult to separate from the images that defined it: smoke pouring from the Twin Towers, people running through the streets of Lower Manhattan, the damaged Pentagon and a scarred field in Pennsylvania. For a growing number of younger Americans, those events are now history rather than memory.
Watch: 25th Anniversary September 11 Remembrance Ceremony
Americans are gathering Friday to mark 25 years since the September 11, 2001 terrorist attacks. Watch the anniversary remembrance ceremony below as the nation honors the 2,977 victims killed that morning and those whose lives were forever changed by the attacks.
Alternate Stream Link: Watch directly on YouTube
America Marks 25 Years Since September 11
Memorial ceremonies are being held Friday at all three attack sites as the nation observes the 25th anniversary. At the National September 11 Memorial in New York City, relatives of the victims are again reading their names aloud at the site where the Twin Towers once stood.
Vice President JD Vance is attending the Ground Zero observance alongside former Presidents Bill Clinton, George W. Bush, Barack Obama and Joe Biden. President Donald Trump is marking the anniversary at the Pentagon, while another commemoration is being held at the Flight 93 National Memorial near Shanksville, Pennsylvania.
This year’s New York ceremony also includes a moment of silence for people who survived the attacks but later died from illnesses linked to exposure to toxic dust and debris. Thousands of people who worked, lived or responded in the affected areas have suffered long-term health consequences in the years since 2001.
What Happened on September 11, 2001
The attacks unfolded over less than two hours.
American Airlines Flight 11 struck the North Tower of the World Trade Center at 8:46 a.m. At first, there was confusion about whether the crash might have been an accident. That uncertainty ended at 9:03 a.m., when United Airlines Flight 175 struck the South Tower in full view of television cameras and people watching across New York City.
At 9:37 a.m., American Airlines Flight 77 crashed into the Pentagon in Arlington, Virginia. At 9:59 a.m., the South Tower collapsed.
United Airlines Flight 93 crashed near Shanksville at 10:03 a.m. after passengers and crew members, having learned through phone calls what had happened to the other planes, attempted to retake control of the aircraft. The hijackers had intended to strike another target in Washington, with the U.S. Capitol or White House considered likely possibilities.
At 10:28 a.m., the North Tower collapsed.
By the end of the morning, the World Trade Center complex was devastated, a section of the Pentagon was badly damaged and thousands of people had been killed.
Who Attacked the United States?
The 19 hijackers were al-Qaeda operatives who had received training from the terrorist organization led by Osama bin Laden. The FBI and the bipartisan 9/11 Commission documented al-Qaeda’s planning, recruitment and preparation for the attacks, which had developed over a period of years.
Al-Qaeda had declared the United States its enemy well before September 2001. The organization was responsible for the 1998 bombings of U.S. embassies in Kenya and Tanzania, which killed 224 people, including 12 Americans. In October 2000, al-Qaeda attacked the USS Cole in Yemen, killing 17 American sailors.
The World Trade Center had also been targeted by Islamist terrorists in 1993, when a truck bomb exploded beneath the complex, killing six people and injuring more than 1,000.
The bipartisan 9/11 Commission identified the enemy behind September 11 as Islamist terrorism, particularly al-Qaeda and the radical ideology that sustained it. Bin Laden and al-Qaeda framed their campaign in religious terms, promoted violent jihad against the United States and deliberately targeted civilians in pursuit of their goals.
September 11 was the culmination of years of planning by a terrorist organization motivated by a radical Islamist ideology. Nineteen hijackers boarded four civilian airliners that morning intending to murder as many people as possible and strike some of the most recognizable symbols of American economic and military power.
The People Who Ran Toward the Danger
September 11 is remembered for the scale of the attack, but also for the response of people who found themselves in the middle of it.
Firefighters, police officers and other emergency personnel entered the World Trade Center while thousands of people were trying to escape. Among those killed were 343 members of the New York City Fire Department, along with officers from the New York Police Department, Port Authority Police Department and other emergency services.
Inside the towers, office workers helped injured colleagues down stairwells and strangers assisted one another through smoke and darkness. Outside, first responders continued moving toward the buildings even as debris fell around them.
The passengers and crew aboard Flight 93 also knew that the situation had changed. After learning that other hijacked airplanes had been used as weapons, they decided to act. Their attempt to retake the aircraft prevented the hijackers from reaching Washington, although everyone aboard the plane was killed.
The Country Changed After 9/11
The effects of September 11 quickly reached far beyond New York, Washington and Pennsylvania.
Congress created the Transportation Security Administration, and the federal government later established the Department of Homeland Security. Airport security became far more restrictive, cockpit doors were reinforced, intelligence agencies were reorganized and surveillance powers expanded as the government tried to prevent another large-scale attack.
Many security measures that are routine today were rare or nonexistent before 2001. Travelers became accustomed to longer airport screening lines, restrictions on liquids, watch lists and other procedures that became part of everyday life in the years after the attacks.
The attacks also led directly to war in Afghanistan. U.S. forces entered the country weeks after September 11 to target al-Qaeda and remove the Taliban government that had allowed the organization to operate there. The war lasted nearly 20 years and ended with the withdrawal of U.S. forces in 2021 and the Taliban’s return to power.
The broader War on Terror shaped American foreign policy for much of the next two decades. It influenced military deployments, intelligence operations, surveillance policy and political debates over the balance between national security and civil liberties.
The Human Toll Continued for Years
The human toll of September 11 did not end when the fires went out.
Firefighters, police officers, construction workers, residents and others were exposed to a toxic mixture of smoke, chemicals and pulverized building materials around Ground Zero. In the years that followed, cancers, respiratory illnesses and other serious conditions were diagnosed among people who had worked or lived in the affected areas.
Congress eventually created and expanded programs to provide medical monitoring, treatment and compensation for people suffering from 9/11-related illnesses. For many families, the consequences of the attacks have continued for decades.
This year’s 25th-anniversary observance in New York reflects that reality with an additional moment of silence for those who survived the attacks themselves but later died from exposure-related illnesses.
A Generation Born After September 11
The passage of 25 years has created another challenge: millions of Americans have no firsthand memory of the attacks.
A person born on September 11, 2001, is now 25 years old. Today’s schoolchildren know the Twin Towers mainly through photographs and video. They learn about the attacks from parents, teachers, museums and memorials rather than from personal experience.
That makes the historical details increasingly important. The number 2,977 can become abstract with time. Those victims were office workers, airline passengers, firefighters, police officers, military personnel, government employees, restaurant workers, visitors and travelers who began that Tuesday expecting an ordinary day.
Preserving the history also means remembering who carried out the attacks, why they were carried out and how the United States responded. The passage of time does not make those facts less important.
Twenty-Five Years Later
The country that marks the 25th anniversary is very different from the one that woke up on September 11, 2001. The wars that followed have ended, the skyline of Lower Manhattan has been rebuilt and an entire generation has grown up without any memory of the attacks themselves.
But the losses remain personal for thousands of families. The names read aloud each year in New York, at the Pentagon and in Pennsylvania belong to people whose lives ended in a matter of hours because 19 al-Qaeda terrorists carried out a coordinated attack on the United States.
The story of September 11 is also one of courage. First responders entered buildings others were fleeing. Passengers aboard Flight 93 fought back after learning what the hijackers intended to do. Rescue and recovery workers spent weeks and months searching through the wreckage, often at great cost to their own health.
Twenty-five years later, remembering September 11 means remembering all of it: the victims, the people who tried to save them, the ideology that drove the attackers, the wars and policies that followed, and the families that have carried the consequences ever since.
For those who remember the day clearly, September 11 can still feel much closer than 25 years ago. For those born afterward, the responsibility is different but no less important: to understand what happened and to remember the people who were lost.