Early on the morning of September 11, 2001, the United States seemed to be just about the safest place in the world to live.
The nation hadn’t been attacked on its own soil since the bombing of Pearl Harbor six decades before.
War seemed like something that happened elsewhere. Perhaps, that, more than anything, is what made the massive terror attacks of that day so shocking.
The 9/11 attack on the World Trade Center and the Pentagon was unprecedented in the scale of its destruction and the immediacy of its visual impact.
Americans had heard or read about other historical disasters, but this was the first to be witnessed by hundreds of millions of citizens as it occurred. The impact on society was dramatic and long lasting.
The first plane to hit its target was American Airlines Flight 11. It was flown into the North Tower of the World Trade Center complex in Lower Manhattan at 8:46 am.
Within minutes, live televised images of the burning skyscraper were breaking into the morning news. Many believed it must have been an accident.
Seventeen minutes later at 9:03 am, the World Trade Center’s South Tower was hit by United Airlines Flight 175.
As a third plane hit Pentagon-the headquarters of the US armed forces-outside Washington D.C., and a fourth plane crashed in a field in Pennsylvania, few believed this could be anything but an attack on the United States.
In the World Trade Center, people were trapped on the floors above the impact zone, unable to escape through damaged stairwells.
Some scrambled toward the roof, hoping for rescue from above, only to find the way blocked.
Some returned to their desks. They called home. They said good-bye before the floors collapsed beneath them as first the south tower and then the north tower fell, turning thousands, in a moment, into dust.
The fourth, and final flight, United Airlines Flight 93, crashed near Shanksville, Pennsylvania, southeast of Pittsburgh, at 10:03 a.m. after passengers fought the four hijackers. Flight 93’s target is believed to have been either the Capitol or the White House.
Flight 93’s cockpit voice recorder revealed crew and passengers tried to seize control of the plane from the hijackers after learning through phone calls that Flights 11, 77, and 175 had been crashed into buildings that morning.
Once it became evident that the passengers might gain control, the hijackers rolled the plane and intentionally crashed it.
The attacks are the deadliest terrorist attacks in world history, causing the deaths of 2,996 people (including the hijackers) and injuring more than 6,000 others.
The death toll included 265 on the four planes (from which there were no survivors); 2,606 in the World Trade Center and in the surrounding area; and 125 at the Pentagon.
Most who died were civilians; the rest included 343 firefighters, 72 law enforcement officers, 55 military personnel, and 19 terrorists.
At least 200 people fell or jumped to their deaths from the burning towers (as exemplified in the photograph The Falling Man), landing on the streets and rooftops of adjacent buildings hundreds of feet below.
After New York, New Jersey lost the most state citizens. More than 90 countries lost citizens in the attacks; for example, the 67 Britons who died were more than in any other terrorist attack anywhere.
The destruction of the World Trade Center and nearby infrastructure seriously harmed the economy of New York City and created a global economic recession.
Many countries strengthened their anti-terrorism legislation and expanded the powers of law enforcement and intelligence agencies to prevent terrorist attacks.
The U.S. and Canadian civilian airspaces were closed until September 13, while Wall Street trading was closed until September 17.
Many closings, evacuations, and cancellations followed, out of respect or fear of further attacks.
Cleanup of the World Trade Center site took eight months and was completed in May 2002, while the Pentagon was repaired within a year.
In the immediate aftermath of the attacks, suspicion quickly fell onto al-Qaeda.
The United States government under the George W. Bush administration formally responded by launching the War on Terror and invading Afghanistan to depose the Taliban, which had not complied with U.S. demands to expel al-Qaeda from Afghanistan and extradite al-Qaeda leader Osama bin Laden.
Bin Laden fled to the White Mountains where he came under attack by U.S.-led forces, but managed to escape.
Although bin Laden initially denied any involvement, in 2004 he formally claimed responsibility for the attacks.
Al-Qaeda and bin Laden cited U.S. support of Israel, the presence of U.S. troops in Saudi Arabia, and sanctions against Iraq as motives.
After evading capture for almost a decade, bin Laden was located in a hideout in Abbottabad, Pakistan, and subsequently killed by the U.S. military on May 2, 2011.
(Photo credit: Wikimedia Commons / Library of Congress / US Army Archives).