For most Americans, today is just another busy Tuesday. There are school lunches to pack, business meetings to attend, sports teams to cheer, an evening out to enjoy.
Erin Jackman is sure she will see scores of New Yorkers hurry past her this morning on their way to the office, the subway or an appointment.
Her plans are much more somber: She will be at Ground Zero for the recitation of the names of the nearly 3,000 people who died in the 2001 terrorist attacks. Her 23-year-old sister, Brooke, was on the 104th floor of the north tower when it crumbled.
"It's a very hard thing to see the city go on like it's nothing," Erin says. "People are going to work and doing their thing."
The Sept. 11 attacks still elicit sadness, anxiety and anger for many. But as we enter the 11th year after that tragic day, it begs the question:
How will the nation mark the occasion as the horrors of that day - as well as the victims and heroes - fade from our collective memories?
In decades to come, will 9/11 anniversaries remain a moment frozen in the nation's consciousness? Or will they be more like time-softened remembrances of other iconic tragedies in U.S. history: Pearl Harbor (Dec. 7, 1941), President John F. Kennedy's assassination (Nov. 22, 1963) and the space shuttle Challenger explosion (Jan. 28, 1986)?
Nearly 70% of Americans say they somewhat or strongly agree with this statement: "I have moved on from (the events of) Sept. 11," according to a new American Pulse Survey.
Media attention to Sept. 11 has already waned, says Brian Monahan, a sociology professor at Marywood University in Scranton, Pa., who has researched coverage of the attacks.
"Last year, you couldn't avoid it," he says. "This year, you have to go out of your way to find it."
The 2011 press coverage was amplified by the 10-year anniversary and the opening of the National September 11 Memorial. In May of that year, the killing of al-Qaeda leader Osama bin Laden also dominated the news.
But even in the years leading up to the one-decade mark, news coverage had declined. That's what happens when you combine the passage of time with the constant retelling of a story, Monahan says. "As time goes by, you truncate some of the details. The narrative gets streamlined."
Anniversary marked in different ways
Almost every American adult remembers what he or she was doing when news of the Sept. 11 attacks spread, according to a Pew Research Center survey taken in August 2011. Three-quarters say they were affected a great deal emotionally.
Many witnessed the falling towers on TV that morning, and then relived those shocking moments again and again as news stations replayed the video. There was non-stop coverage of panicked workers fleeing the World Trade Center and the Pentagon, and scenes of the crashed commercial airline carnage in a field near Shanksville, Pa.
Terror gripped those fearing that a loved one was on a hijacked plane. Tension rose as Americans wondered what terrorist attacks might follow.
Today, how people live out the anniversary varies greatly.
Half of Americans will observe today in an informal way and 12% will do it in a formal manner, according to the American Pulse Survey. About 30% said they will not do anything different today, and 8% said they didn't have an opinion.
Some attend local tributes, watch the reading of the victims' names on TV or do volunteer work, which has become linked to the anniversary.
Many Americans will mark the events of Sept. 11 by participating in a day of service. For instance, the non-profit MyGoodDeed asks people to make a commitment to one commemorative act, such as thanking a firefighter or volunteering at a community center, and to share it on 911day.org.
On a local level, groups such as Walk With Joe, a Manalapan, N.J., organization named after Patrick "Joe" Driscoll, who was aboard Flight 93. It has raised more than $250,000 for charities through events such as memorial 5K walks.
Others keep a schedule similar to any other day, planning breakfast meetings, dentist appointments and haircuts.
There are even those who reserve the date for large-scale affairs such as conferences, networking events and weddings. Last year, 1,712 people exchanged vows on Sunday, Sept. 11, according to wedding registration data compiled from TheKnot.com and WeddingChannel.com users. That's nearly double the number of those who did so the last time Sept. 11 fell on a Sunday, which was 2005.
Pamela Bittner, who lost her twin brother, Jeffrey, in the World Trade Center, is surprised at how many people plan outings on a day that changed her life. "It still boggles my mind that someone can have an event that starts on the 11th," she says. "It's just another day of business for some people. It will never be that for me."
She will spend today with close friends, as well as try something that makes her feel a bit uneasy: attending a reading of victims' names.
"Typically I don't like to spend the day out in public or with a lot of people," says Pamela, who lives in Boston. "For me it's a very private thing."
But with 11 years gone, she is open to new methods of commemorating her brother's death. "It is the start of a new decade" since his death, she says. "You start to look at things differently. You figure out what the next phase is going to look like."
Yet her feelings of loss remain. Jeff was her friend, a confidant, and - as a "big brother" born one minute before her - also her protector.
"You don't ever get over it (the loss) but you figure out a new way to be with it," Pamela says.
Mourning vs. moving on
Some aren't yet ready for change. For instance, there was a backlash from victims' families after New York City Mayor Michael Bloomberg, suggested last year that future Sept. 11 ceremonies may not include the recitation of victim names.
It's tough to navigate between mourning and moving on, says Sheila Erlich, a psychologist who counseled workers who saw the planes crash into the twin towers as well as those who lost loved ones that day.
Still, it's important to work at recovering from trauma, she says. "People sometimes feel guilty. They feel like they're betraying the lost person by moving on. But feeling the guilt is not healthy. They all have a right to a life," Erlich says.
Psychologist Robin Goodman says that as time goes by, new life experiences start to accumulate and add to one's history. "So it is only natural -and necessary - to be engaged in living, which is different than forgetting," she says.
At the same time, commemorating the deaths of loved ones, such as at the annual Sept. 11 recitation of the victims' names, is "very helpful and therapeutic," Erlich says.
For Brooke Jackman's family, that rite is incredibly meaningful.
"I hope they keep reading the names," Erin says. "It just feels like a good routine, a good way to be with other people who feel as we do."
Michael Timothy, a former stockbroker who was at the World Trade Center the morning of the attacks, says the anniversary is emotional for him. But some others in his Sandpoint, Idaho, community are indifferent, even callous, about the day.
"I know that as time goes on, people will forget more and more," he says. Yet he says it's important that all Americans reflect on that day and the lives that were lost, even if it's "just a quick five-second thought process."
Brooklyn resident Valerie Reiss will take more time to contemplate the day: "It's important to step into the spirit of quiet remembrance."
On the morning of Sept. 11, she was running late for her temp job on the 100th floor of the south tower. From the street, she saw flames. As she hurried away, she heard the second plane hit.
Reiss has clear memories of the rising gray dust and the open pit that remained after the buildings fell. But she focuses instead on how people rallied to help each other in the aftermath. "I want to remember our collective ability to take care of each other and love each other," Reiss says.
No forgetting the date: 9/11
Of course, it's nearly impossible to forget the harrowing and heroic events of Sept. 11. Four planes highjacked. Two crashed into the iconic twin towers. One slammed into the Pentagon. Another brought down in a field near Shanksville, Pa. Firefighters running into buildings as workers streamed out.
And there's a major memory aid that should stand the test of time: The assault is known simply by the date it occurred. It is "9/11" or "Sept. 11" - not "the day the twin towers collapsed" or "the al-Qaeda attack."
So while some may forget Pearl Harbor Day or the date of Kennedy's assassination, there is no overlooking this date. It comes up on cellphone screens, Outlook calendars and printed daybooks.
Even with the reminders, Erin wonders how long those who help keep her sister's legacy alive - such as Brooke's high school friends who give a scholarship in her name - will continue those efforts.
"Every year, it's in the pit of my stomach. Is this going to be the year when they say 'Enough already'?" she says. "As time goes on, (I think), 'Will I hear from my sister's friends? Will they remember?' But they still do."
Those fears are normal, psychologist Erlich says. Even as time brings about changes, it's unlikely that a person, or the tragic events, will be forgotten. The Holocaust was more than 60 years ago, she says, but people still crowd into museums to learn the history and honor those who died.
While the official Sept. 11 museum in Manhattan hasn't opened, there are other established areas for those who want a meaningful place to reflect on the attacks, such as the memorials at Ground Zero and the Pentagon, as well as the Flight 93 memorial near Shanksville.
"We commemorate and memorialize every day," says Michael Frazier, spokesman for the New York City memorial. "We are an institution dedicated to this."
Tragic and uplifting reminders
Beyond museums and monuments, there are countless other indelible reminders of Sept. 11.
There are the lingering mental and physical ailments of those who cleared Ground Zero.
There are Sept. 11 books and blogs as well as the "never forget" tattoos.
The Brooke Jackman Foundation, which fosters child literacy, has distributed nearly 100,000 books since its 2001 inception. On Saturday, it hosted a read-a-thon to commemorate Brooke and promote the importance of reading.
In a public atrium down by the World Trade Center, dozens of kids gathered to hear books read aloud by performers including actress Rosie Perez and cast members from the Broadway play Spider-Man: Turn off the Dark.
Also among the readers were those who experienced the devastation of Sept. 11 first hand. The Jackman family was there, as were members of the New York City Fire Department, which lost 343 members that day.
Most of those children in attendance weren't even born when those attacks occurred.
While time passes and the events of Sept. 11 may fade, what remains important is this: helping others - such as these kids - while honoring Brooke, Erin says.
"It doesn't matter if there's attention," she says. "It's about Brooke and it's about my family. It's the day we remember my sister."
By Laura Petrecca