Twenty-five years ago, a clear Tuesday morning in New York City became the scene of the deadliest terrorist attack in American history and a defining moment of the 21st century. On September 11, 2001, nineteen al-Qaeda hijackers took control of four commercial airliners and used them as weapons. Nearly 3,000 people were killed in less than two hours, changing global politics, air travel, and national security for the generation that followed.
Today, on the 25th anniversary, families of the victims are gathering at the 9/11 Memorial plaza in Lower Manhattan, at the Pentagon, and in a quiet field near Shanksville, Pennsylvania. They will read the names of those lost and observe the exact moments when the world changed. Below is a breakdown of what happened on September 11, 2001, how the day unfolded, and what the attack means twenty-five years later.
What Was the 9/11 Attack?
The 9/11 attacks were a coordinated set of four suicide hijackings by 19 militants from the terrorist group al-Qaeda, led by Osama bin Laden. The hijackers took over four US commercial jets soon after takeoff. Two planes hit the Twin Towers in New York City, one struck the Pentagon in Virginia, and the fourth crashed in a field near Shanksville after passengers tried to stop the hijackers.
When the attacks ended, 2,977 people had been killed, not counting the 19 hijackers. This made it the deadliest terrorist attack ever recorded in the United States.
The Full Timeline: How September 11, 2001 Unfolded
7:59 a.m. – American Airlines Flight 11 leaves Boston. The Boeing 767, heading to Los Angeles with 92 people on board, took off from Logan International Airport. Five hijackers, led by Mohamed Atta, were among the passengers.
8:14 a.m. – United Airlines Flight 175 leaves Boston. Also bound for Los Angeles, this second Boeing 767 carried 65 people, including five more hijackers.
8:19 a.m. – Flight attendants on Flight 11 alert ground staff. Crew members reported the hijacking, giving authorities their first sign that something was seriously wrong.
8:46 a.m. – Flight 11 hits the North Tower. The hijacked jet crashed into the upper floors of 1 World Trade Center, between the 93rd and 99th floors, killing everyone on board and hundreds inside. Early news reports called it a possible accident.
9:03 a.m. – Flight 175 hits the South Tower. As television cameras focused on the burning North Tower, the second hijacked plane crashed into 2 World Trade Center between the 75th and 85th floors. It was now clear that America was under a coordinated attack.
9:37 a.m. – American Airlines Flight 77 hits the Pentagon. After being hijacked soon after leaving Washington Dulles International Airport, the Boeing 757 was flown into the west side of the Pentagon, killing all 64 people on board and 125 military and civilian personnel inside.
9:59 a.m. – The South Tower collapses. Fifty-six minutes after being hit, the 110-story tower fell in about 10 seconds, sending a huge cloud of dust and debris through Lower Manhattan.
10:03 a.m. – United Airlines Flight 93 crashes in Shanksville, Pennsylvania. Passengers and crew on the fourth hijacked plane, after learning about the earlier attacks through phone calls, tried to retake control by storming the cockpit. The plane crashed in a field near Shanksville, killing all 44 people on board. Investigators later believed the hijackers had planned to target either the US Capitol or the White House.
10:28 a.m. – The North Tower collapses. The second tower fell 102 minutes after being hit, finishing the destruction of the World Trade Center complex and covering nearby streets in ash.
By the end of the day, all air travel in the United States was grounded for the first time ever, financial markets were closed, and President George W. Bush addressed the nation from the Oval Office, saying the attacks would not go unanswered.
The Human Cost
The final death toll from September 11 stands at 2,977 victims, not including the 19 hijackers. That figure includes:
- 2,753 people killed at the World Trade Center site, including office workers, visitors, and 343 members of the New York City Fire Department who died attempting rescues
- 184 people killed at the Pentagon, including passengers on Flight 77
- 40 people killed aboard United Flight 93 in Pennsylvania
- Citizens from more than 90 countries, making it one of the most internationally devastating single-day attacks in modern history
In the years since, the number of deaths linked to 9/11 has continued to rise. Thousands of first responders, cleanup workers, and lower Manhattan residents have died from cancers and respiratory illnesses caused by toxic dust at Ground Zero. The FDNY and health researchers now track these deaths separately as a lasting consequence of the attack. The 9/11 Memorial now honors 2,983 names, including the six people killed in the 1993 World Trade Center bombing.
Who Was Behind the Attack?
The 9/11 Commission, a bipartisan group set up by Congress to investigate the attacks, found that al-Qaeda, led by Osama bin Laden, planned and financed the hijackings from bases in Afghanistan, where they were protected by the Taliban government. Fifteen of the nineteen hijackers were Saudi nationals. The main planner, Khalid Sheikh Mohammed, was later captured and is still in US custody at Guantanamo Bay, waiting for a long-delayed military trial.
Bin Laden was killed by US Navy SEALs in a raid on his compound in Abbottabad, Pakistan, in May 2011, nearly a decade after the attacks.
What Changed After 9/11
The attacks led to major changes that are still felt today, even twenty-five years later:
The War on Terror. Weeks after the attacks, the US launched an invasion of Afghanistan to topple the Taliban and dismantle al-Qaeda’s safe haven, beginning America’s longest war, which formally ended with the withdrawal of US troops in August 2021. The war in Iraq followed in 2003, justified in part by since-discredited claims about weapons of mass destruction.
Homeland security overhaul. The attacks led directly to the creation of the US Department of Homeland Security and the Transportation Security Administration, fundamentally changing how Americans fly, travel, and move through public spaces. Airport security screening, ID checks, and liquid restrictions that travelers now take for granted all trace back to policy changes made in the months after 9/11.
Surveillance and civil liberties. The USA PATRIOT Act, passed just weeks after the attacks, expanded government surveillance powers dramatically, a shift that continues to fuel debate over the balance between national security and civil liberties.
Global geopolitics. The attacks redrew alliances, triggered NATO’s first-ever invocation of Article 5, its collective defense clause, and reshaped US relations across the Middle East and South Asia for decades.
Marking 25 Years: How the Anniversary Is Being Observed
This year’s anniversary is especially significant as it marks twenty-five years since the attacks. In New York, families of victims are gathering at the Memorial plaza for an in-person reading of all 2,983 names. There will be seven moments of silence instead of the usual six, with the extra moment honoring those who have died from 9/11-related illnesses. The ceremony started at 8:30 a.m., with the first moment of silence at 8:46 a.m., the exact time Flight 11 hit the North Tower in 2001.
At the Pentagon, officials are holding their own ceremony, while in Shanksville, a remembrance service honors the passengers and crew of Flight 93. The FDNY has planned a full year of 25th-anniversary events, including a health report on 9/11-related illnesses among firefighters, a documentary about FDNY chaplain Father Mychal Judge, and a podcast series hosted by actor and veterans’ advocate Gary Sinise.
As night falls, the Tribute in Light will once again shine over the New York skyline with its two columns of blue light. This temporary but now annual display echoes the fallen towers and can be seen for miles across the city.
Twenty-five years after the attacks, September 11 is still seen as a turning point in modern history. For people born after 2001, the day is history, not memory, but its effects, from airport security to global politics, still shape daily life. As survivors, first responders, and victims’ families mark this anniversary, the day stands as both a time to remember and a reminder of how much one morning can change a nation.
