NEW YORK -- Alyssa Henry was in the eighth grade when two airplanes struck the World Trade Center.
She can remember what she wore that day (gray sweatpants and a black T-shirt), what class she was in (Spanish), even what she whispered to a friend when she first heard that terrorists had attacked the nearby island of Manhattan.
"What's a terrorist?" Henry recalls asking. "I had never heard the word before, and I guess it just wasn't in my vocabulary. Now, of course, it is."
Today's American 20-somethings came of age in the shadow of the twin towers' collapse. For many, the 9/11 attacks marked the first time they could recall feeling truly vulnerable.
"On 9/11, it suddenly became very clear: You are not safe," said Henry, now 23 and a student at Syracuse University, where she is studying for a master's degree. "These malicious forces were attacking not only our country, but my city. I don't think my generation will ever truly forget what that amount of fear felt like."
It's difficult to determine how any one event might shape an entire nation, especially one as geographically and politically diverse as the United States -- let alone an entire generation. But researchers who study the "millennial" generation -- many of whose members are now in their 20s -- say the studies they've conducted show that 9/11 may have had a certain political effect on young people, particularly on those residing in the Northeast.
Neil Howe, an author and historian who is credited with creating the generational moniker for young people born between 1982 and 2003, doesn't believe the idea that generations sit idly by, waiting to be shaped by a major event in history. He says he had already glimpsed what millennials would come to value as adults, long before the 2001 terrorist attacks.
"Big events like 9/11 don't so much shape a generation as reveal a generation," said Howe. "Generations are shaped by their place in history, and it's an orientation that starts in childhood. Prior to 9/11, millennials were already well on their way to becoming an entirely different generation that the ones that came before."
Before 9/11, when many were still young kids, Howe says millennials were sheltered, generally trusting of government and showed a high propensity for community and political engagement. It's an orientation they learned from their parents, Howe says.
Still, Michael D. Hais, who writes about millennials, hypothesizes that the feeling of vulnerability induced by 9/11 that many experienced as children may have helped foster the political beliefs some have grown to adopt as young adults.
"For millennials, 9/11 is their equivalent of Pearl Harbor," said Hais. "Most were in grade school, and for many, the memories of that day deeply affected their perception of the world and their place in it."
Hais and his colleague, Morley Winograd, recently co-authored "Millennial Momentum: How A New Generation Is Remaking America." They observed that growing up in era of increased security measures following 9/11 may have been especially significant for millennials.
Like Howe, Winograd observed parents who were already prone to coddling their children suddenly upped the ante following the terrorist attacks.
"To the degree that millennials already had protective parents who were concerned with the general safety of their kids, they doubled down on the issue of choosing to raise their kids in a protected and concerned world," Winograd said.
The two scholars say the consequences of 9/11 include an impact on millennials' political identifications and affiliations. Hais and Winograd found millennials are far more likely to identify as liberals than older generations are. They also found that 9/11 fueled a deep and abiding sense of patriotism in many young people.
"Sept. 11 reinforced the heroic nature of people in uniform -- be it policemen, firemen or members of the armed forces," said Winograd. "Going forward, that will continue to leave a pro-institutional attitude on many of the generation. They see the value of institutions in making the world safer."
COMING OF AGE IN A POST-9/11 WORLD
Ashley Smalls, 19, who grew up in Cypress Hill, Brooklyn, never thought a whole lot about how people in the rest of the world might view the United States before 9/11.
"It made me grow up a little bit faster," said Smalls, who now attends Pennsylvania State University. "It made me realize that the world isn't made of all sunshine and rainbows, that we have these enemies and that there's this hatred aimed directly at us."
Smalls reported feeling more patriotic in the years following 2001 and says she has long identified as a Democrat. She also said the aftermath of 9/11 filled her with a sense of the need for tolerance.
As an African American, Smalls was familiar with the stereotypes and assumptions people made simply by looking at the color of her skin. So when her classmates taunted those of Muslim faith, or made fun of individuals wearing turbans or headscarves, Smalls says she admonished their behavior.
"For this generation, the lesson that comes out of this is that we're all connected," said John Della Volpe, who directs polling at Harvard University's Institute of Politics. "Everything is connected -- for good or for ill."
Della Volpe cited the 2008 election of President Obama as evidence of shifting foreign policy priorities, particularly between older and younger Americans. For most millennials, 2008 marked the first time that many could vote in a presidential election. According to a Pew report, voters between the ages of 18 and 29 cast their ballots in favor of Obama by a ratio of more than two to one in the general election against John McCain.
Della Volpe believes a lot can be gleaned from millennials' behavior in the 2008 election. "When Obama talked about sitting down with any head of state, regardless of where they came from, that essentially sealed the deal with a significant number of young voters," he said.
But while a majority of millennials voted for Obama in 2008, a July Pew survey found that Republicans are making inroads with under-30 voters.
"While these voters remain the most Democratically oriented generation today, the advantage has narrowed substantially since 2008," Pew found. "Currently, 52 percent of millennial voters are Democrats or lean to the Democratic Party while 39 percent are Republicans or lean to the GOP. This 13-point edge is less than half the size of the 32-point edge Democrats held three years ago."
The short electoral record makes it difficult to tell how 20-somethings will lean politically, or how the legacy 9/11 will affect this generation as it continues to mature.
Whether millennials lean Democrat or Republican, Della Volpe sees a generation of young people keenly aware of their own country's place in the post-9/11 world.
In a survey Della Volpe conducted five years after 9/11, he found 65 percent of of respondents aged 18 to 24 reported that the terrorist attack had altered their view of politics and government, while 31 percent reported feeling cynical and distrustful of the political powers that be.
"That simple frame really does speak to the difference between millennials and older generations," said Della Volpe. "Sept. 11 made them realize very quickly how everything is connected and how not engaging with our enemies is no longer an option."
THE VILLAIN IS DEAD
While many millennials may be more inclined towards compromise -- such as support for multilateral, rather than unilateral, military intervention -- others count Osama bin Laden as an exception, and a deserving target. Earlier this spring, the killing of the al Qaeda leader and architect of the 9/11 attacks elicited a strong show of celebration and support, particularly among 20-somethings on college campuses.
"Osama bin Laden was the man we were taught to hate," said Ryder, a 22-year-old student at Hamilton College, adding that bin Laden's death "was a triumphant moment and something I'll never forget."
"I wanted to do a fist-pump off the tallest building possible," said Ryder, who grew up in Brooklyn's Park Slope and was in seventh grade on 9/11. "This was the man who had caused all of this grief and all of this sorrow and finally he was dead."
Smalls first learned of bin Laden's death on her Twitter feed, while staying up late studying for finals. Before going out and participating in a celebratory parade through campus, she updated her Facebook status to read: "RIP: Rest In Piss!"
"The 9-year-old inside of me who had to witness 9/11 felt happy that he was finally gone," said Smalls. "We were so young and it impacted us at such young age."
For Ryder, the 10th anniversary of the 9/11 attacks is all that more meaningful now that the decade's defining villain is dead. She said she doesn't believe killing should be celebrated with more killing, but she does think many in her generation can finally rest a bit easier now that bin Laden is gone.
But even with bin Laden dead, some of Ryder's peers say the world still feels far from safe. Henry says she can't help but feel like a little girl again each September.
"Every time that 9/11 comes around, I still feel like I'm 13," said Henry, who plans to commemorate the 10th anniversary of the attacks with her friends at Syracuse. "The day still resonates so strongly for me. Even now, tears come to my eyes. I still feel afraid."
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more