Twenty-five years after the Sept. 11, 2001, terrorist attacks, the tragedy remains one of the most significant historical events in the lives of many Americans.

An Ipsos poll found that about half of U.S. adults identified the 9/11 attacks when asked, without being given a list of choices, to name the most important historical events of their lifetimes.

The attacks ranked ahead of several major events that followed, including the COVID-19 pandemic and the elections of Presidents Barack Obama and Donald Trump.

The findings illustrate the lasting impact of Sept. 11, even as a growing share of the U.S. population is too young to remember the attacks or was not yet born when they occurred.

Among Americans who experienced the events of that day, an overwhelming majority say they remember where they were when they first learned about the attacks. About two-thirds of Americans also say Sept. 11 affected the country “a great deal.”

Despite the lasting significance of the tragedy, relatively few Americans say they plan to personally commemorate its 25th anniversary. According to the Ipsos poll, only about 1 in 10 adults plans to mark the anniversary in some way.

For younger Americans, Sept. 11 is an event learned about through history lessons rather than personal experience. A Pew Research Center poll conducted in August found that about 6 in 10 adults born after the attacks first learned about 9/11 in school or through class assignments.

A quarter-century later, the polling suggests Sept. 11 continues to occupy a unique place in the nation’s collective memory, bridging generations that witnessed the attacks firsthand and those who have come to understand their significance through history.

The September 11 attacks, often called 9/11, were a set of four coordinated suicide attacks by the terrorist group al-Qaeda against the United States.

Nineteen al-Qaeda terrorists hijacked four commercial airplanes. Two planes hit the Twin Towers in New York City, causing both to collapse. A third plane crashed into the Pentagon near Washington, D.C. Passengers and crew fought back on the fourth plane, which crashed in a Pennsylvania field.

The tragic events resulted in 2,977 fatalities…. making it the deadliest terrorist act in world history.

World Trade Center
2,753 deaths (including 343 firefighters, 23 NYPD, and 37 Port Authority officers)

The Pentagon
189 deaths (64 on Flight 77, 125 civilian/military personnel)

Flight 93 (Pennsylvania Field)
44 deaths (all passengers, crew, and hijackers)

Today marks the 25th anniversary of the tragedy, with solemn memorial ceremonies held across the United States and throughout US citizens worldwide.