The images are unforgettable — smoke billowing from the World Trade Center towers in New York, from the Pentagon outside Washington, D.C., and from a field in Shanksville, Pennsylvania after 19 hijackers crashed jetliners along the East Coast, killing nearly 3,000 people on Sept. 11, 2001.
The Pew Research Center revealed that 93% of American adults 30 years and older say they remember specifically where they were on that fateful Tuesday two decades ago.
As the country approaches the 20th anniversary of the attacks, many people are sharing stories of where they were when America changed forever.
"I was in the concourse of the south tower in Sam Goody’s record store to buy a new Walkman radio/cassette player," Annette Gordon-Reed, a professor at Harvard University, told the Havard Gazette. "I had just returned from taking my kids to school, having come up from the subway. I heard a loud "whump," and things began to fall around us."
"Nothing can capture the feeling I had walking out of Carlyle on Union Square and seeing the first tower smoking," Michael Roth told New York University. "At the moment I had no idea what was going on, so I went back in to get my (non-digital) camera. After I came back out, both buildings were gone."
"I was just sitting down to feed my 14-month-old daughter her breakfast and was also watching the Today show," Lara Cuprak told the Connecticut Post. "Things just started getting crazy in NYC and I looked up just as the plane hit the second tower."
But there is a sizable chunk of the U.S. adult population that doesn’t remember details of their personal lives on 9/11 or the day itself — even the children of parents who perished in the attack.
According to NPR, Laurel Homer was 10 months old when her father, LeRoy Homer, was killed as he co-piloted United Airlines Flight 93, the hijacked plane that crashed in Pennsylvania.
"I don't know that much," the 20-year-old told the outlet. "It's something that I just don't ask about a lot."
Researchers say it’s collective memories that define generations. According to a 2016 study from the University of Michigan at Ann Arbor’s Institute for Social Research, events that happened to people between 10 and 30 years old will have the greatest likelihood of defining that generation, such as the Vietnam War generation.
"It is 9/11 that is the defining and dividing event," Jason Dorsey, president of the Center for Generational Kinetics, told Business Insider in 2019. "Either you remember it and all the emotion that goes with it or you don't, and if you don't, then you're in Gen Z."
But some researchers point out that even people remembering where they were 9/11 can be flawed or inaccurate. A 2009 study showed details from flashbulbs memories— the circumstances in which one first learned of a very surprising and consequential (or emotionally arousing) event — can start to fade over the years.
"So if you look at memory for 9/11, pretty much everybody would say, ‘I know where I was, who I was with etc. etc.’ Everyone thinks, ‘Oh, I never would forget that,’" lead investigator Elizabeth A. Phelps told Scientific American. "But we know from a lot of studies from the past 30 years that people aren't necessarily right. You can't even convince people that their memories are wrong. All you can say is that data would suggest your memory's wrong."
But Phelps said those who can’t remember the contextual details of 9/11 shouldn’t be alarmed.
"It's important to remember that the 9/11 attack occurred, right?" she continued. "Knowing the details about how they occurred, who told you about it, doesn't necessarily matter."
This story was reported in Los Angeles.