The morning of September 11, 2001, is one of Aidan Thayer’s first memories.
He was just 3 years old when the terrorist group al-Qaida launched a series of four coordinated attacks against the United States using four hijacked passenger airplanes. Two of the planes crashed into the Twin Towers of New York City’s World Trade Center, while a third was flown into the Pentagon, the Department of Defense headquarters, near Washington. Passengers on the fourth plane, likely bound for the White House, retook control of the aircraft and crashed it into a field in Pennsylvania.
Thayer’s mother picked him up from preschool in the middle of the day, frantic.
She drove to the family home in Springfield, Virginia, a 15-minute drive from the Pentagon. She set Thayer in front of the TV while she desperately attempted to call his father, Bradley Thayer, who was working at the Pentagon that day but evacuated successfully.
“There was this one shaky cam, grainy footage, of the second plane hitting the second tower … constantly on the news,” said the younger Thayer, now 22. “I just remembered that clip looping over and over again, of just seeing the second plane, not very far away, hitting the tower.”
That day, 2,977 people died, as did all 19 of the al-Qaida hijackers, in the single deadliest terrorist attack on U.S. soil.
Nineteen years later, Thayer is a fifth-year undergraduate student at Case Western Reserve University in Ohio, where he triple-majors in physics, mathematics and German. Thayer, despite his near-photographic memory, can only recall some scenes from the day of the attacks.
For older Americans, in contrast, 9/11 remains a vivid memory. Ten years later, 97% of Americans 8 or older at the time could remember exactly where they were when they heard the news, according to a 2011 survey by the Pew Research Center.
For many young people, though, 9/11 is a subject learned secondhand.
“It feels like something that we learned in history books, something like World War Two,” said Christina Liu, 22, from New York City. Liu graduated from New York University last year and will start work this month as an associated development operations engineer at Veeva Systems, a cloud computing company in California.
“It seems very distant to me, despite being an event that happened in my lifetime,” added Liu, who found she couldn’t distinguish her memories of 9/11 from her memories of a massive 2003 power outage dubbed the Great Northeast Blackout.
That’s to be expected, according to research on collective memory, the pools of memory that can define social groups like generations.
In a 2016 study, Howard Schuman and Amy Corning, researchers with the University of Michigan at Ann Arbor’s Institute for Social Research, compared years of survey data on the Vietnam War and 9/11 to predict how generations of Americans might remember the attacks.
Their study supported the “critical years” hypothesis, which suggests that events happening when people are between 10 and 30 years old have the greatest likelihood of defining generations. People older than 30 may consider other, earlier events in their lives as more important to them, while those younger than 10 may be too young to fully understand the significance of an event.
“Earlier events learned about indirectly from school or media … cannot have the same emotional impact regardless of their objective significance,” wrote Schuman and Corning in the study, published in the International Journal of Public Opinion Research.
Some experts think the attacks are what sets the Millennial generation, whose members were born between the early 1980s and mid-1990s, apart from the next one, Generation Z, born beginning in the mid-1990s.
“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.”
Many younger Americans have grown up in a post-9/11 world, where developments like stricter airport security measures, Islamophobia or the U.S. war on terror have always been a reality.
“I wasn’t really cognizant of the devastation caused that day,” said Camryn Permann, 21, from Los Angeles, home to an estimated 70,000 American Muslims, according to a 2010 survey of religious institutions conducted by the Association of Statisticians of American Religious Bodies.
She recalled traveling with Muslim friends and watching them be selected consistently for randomized security checks at airports.
“For me, the only part that I saw was the aftermath of widespread, nationwide Islamophobia that I’ve seen carried out my entire life. That’s been a part of my world since then,” said Permann, who graduated from California State University, Northridge last year, and has been working as a sign language interpreter at Purple Communications since.
Anti-Islamic hate crimes in the U.S. surged in the weeks after 9/11, according to a 2007 study in the Journal of Ethnicity in Criminal Justice. The Islamic Center of Southern California in Los Angeles required police protection after receiving threats in the wake of 9/11, according to photo captions in LAist.
Sadia Fahimul, 22, a friend of Permann’s, remembered her parents warning her that for her own safety, she didn’t need to tell people she was Muslim.
“One time I brought it [being Muslim] up in class … in middle school, and someone asked me, ‘Were you sad when Osama bin Laden got killed?’” said Fahimul, who graduated last year from Bentley University in Massachusetts with a degree in marketing. “I think they genuinely thought that he was part of our religion, when he’s not, he’s an extremist. I don’t even know how I answered, but I remember I was shocked that they even asked me something like that.”
Young people appeared divided on 9/11 and its complicated aftermath.
“It’s just interesting to me [that] what Americans choose to remember and emphasize is an attack against Americans by people from outside of the country, but [they] aren’t as concerned about attacks on people within this country, by people from this country,” Permann said.
Permann pointed at the racism and discrimination she and other Black and LGBTQ Americans face, alongside other minority populations. She also noted the death toll from the ongoing pandemic, which has killed nearly 200,000 Americans, according to Johns Hopkins University.
The surge in Islamophobia, combined with nearly 20 years of American-led conflicts abroad, is why Thayer said he thought it was “incredibly important” for the memory of 9/11 to be passed down to successive generations.
“It’s not to memorialize it,” he said. “To me, you remember it [9/11] because it gives context to everything else that happened.”
After 9/11, the U.S. launched an international military campaign, known as the war on terror, targeting extremist Islamic groups throughout the Middle East, Africa and Asia.
By the end of this fiscal year on September 30, the U.S. will have spent over $6.4 trillion on its post-9/11 military involvement abroad, according to a joint 2019 study from Brown University and Boston University. The study is part of a larger project. Other studies in the collaboration estimated that the conflicts have killed over 800,000 people and displaced 37 million more.
“ I feel like we also need to learn more about the aftermath of it (9/11),” said Fahimul.
“We forget about the … children and families that were killed as a result of the war that came after, all the people that are displaced and, also, people in the United States that were affected by the racism and the hate.”
For Taylor Bair, 21, from North Carolina, this extended death toll is part of the significance of 9/11. One of her friends lost her mother that day. Bair’s grandmother, a flight attendant, was hours from boarding a flight to Washington when the first plane struck the North Tower of the World Trade Center complex.
“How [emotionally] close you were to this event impacts how you see it,” said Blair, a senior at Appalachian State University in North Carolina studying psychology and special education.
“But even though it’s easy to look at something you weren’t connected to and ask why does it matter now, it seriously impacted the lives of thousands of people,” she added. “The people that did die in [9/11], they’re not necessarily people who were well-known, but they had lives and they had family.”
For now, the commemorations continue, despite the pandemic. The 9/11 Memorial and Museum in New York City will reopen September 11 for families of those affected, and for the general public on the next day. Earlier in the week, officials near the site of the crash in Pennsylvania broke ground on a new part of a trail that connects the country’s three main 9/11 memorials.