The first year was marked with a moment of silence, the tolling of bells and a reading of the names of the nearly 3,000 people who died. Those sad rituals continued for the second and third anniversaries of the Sept. 11, 2001, terrorist attacks and will be repeated once again today.
But this time, somewhere between the solemn ceremonies and memorial golf classics, there is also a search for another way to remember that is more official, unified and concrete -- something to help ensure that Sept. 11 is recognized by the public and kept in boldface on every calendar for centuries.
"This one is difficult. Something like 9/11 could, at first, transcend politics and unify us as an American nation, drive us all together," said Katherine Pratt Ewing, a cultural anthropology professor at Duke University. "But the significance seems to change every year.
"The first annual commemoration really was a rallying point. Even the second was," Ewing said. "But as it was used as the jumping-off point for the war in Afghanistan and Iraq, the rallying and unifying function of it became clouded by the politics of war."
Soon after the attacks on the World Trade Center and the Pentagon in 2001, President Bush signed legislation designating each Sept. 11 as Patriot Day and calling for flags to be flown at half-staff each year. Last month, Karen Hughes, a former Bush adviser who is now the State Department's undersecretary for public diplomacy, sent messages to U.S. embassies asking them to come up with a visible way to commemorate the date and remind the world that terrorism is a global menace.
Today, the Pentagon is holding the Freedom Walk, an event planners hope will be replicated across the nation, from small towns to state capitals, in years to come.
Despite these initiatives, some historians predict that popular culture eventually will file Sept. 11 in the same category as Memorial Day, Labor Day and Presidents' Day, holidays laden with a significance and gravitas that were slowly blanched by time.
For a date so freighted with emotion, images and pain, the diluting of the 9/11 anniversary seems impossible to fathom, especially in such places as Washington and New York. But historians said that decades from now, Sept. 11 might take on a different dimension. In other words, Sept. 11 eventually might become another holiday on which many Americans grill hot dogs, go to sales or spend a long weekend at a quaint bed-and-breakfast.
"Throughout the generations, what were powerful and vital holidays take on a less powerful, more consumer-oriented flavor and become something like a picnic day," said Gary M. Laderman, associate professor of religion at Emory University.
Laderman offers the history of Memorial Day, originally called Decoration Day and officially proclaimed in 1868 as a day to decorate the graves of soldiers killed in the Civil War. It was meant as a day of healing, remembrance and unity after the ravages of that conflict, he said.
But Southerners viewed it with skepticism, calling it a northern, political holiday, and many ignored it until well after World War I; by then, Memorial Day was designated as a time to remember Americans who died in any war. For many people today, however, Memorial Day is part of a weekend getaway and the start of summer.
Others said they find a more striking parallel between Sept. 11 and Dec. 7, 1941, the date of the Pearl Harbor attack.
Clarence Davis, 81, was a Navy recruit at Pearl Harbor that day and will never forget. He lives in St. Mary's County, where he keeps after postmasters to observe a congressional order to fly their flags at half-staff on Dec. 7. Every time he comes across a calendar -- in a gift shop, a friend's home, a doctor's office -- Davis flips to December. If the 7th is blank, he finds the printer and urges that Pearl Harbor be noted.
Decades ago, Davis couldn't imagine an era in which Dec. 7 wasn't seared on the collective consciousness. But year after year, the dwindling numbers attending the freezing-cold memorial services on that day tell him a different story.
"It's really disappointing that this happened, that people aren't remembering," Davis said. "Hopefully, we'll never forget what happened on9/11. But it will probably fade, eventually."
Some people said they have struggled to find ways to remember the terrorist attacks without invoking political overtones.
In Washington, about 50 religious leaders met this year to find a way to do this. From Catholics to Muslims to Zoroastrians, the group wrangled with the idea of condemning terrorism in their commemoration.
"Do we talk about terrorism, or don't we? There are many definitions of terrorism. But in the end, we didn't want to focus on that. We wanted to stay away from making it a day that's political," said Erik Schwarz, planning director for the InterFaith Conference of Metropolitan Washington.
They came up with the Unity Walk along Embassy Row in the city, including stops at churches, mosques, temples and memorials.
"We gather in peace to demonstrate our unity, recalling the spirit of togetherness that grew out of9/11," Schwarz wrote in the Unity Walk's mission statement.
Perhaps a day of togetherness will prove too amorphous for the nation to get its arms around. Americans might need something more tangible.
In California, a university's memorial garden is named for one victim; a Delaware baseball field is named for another; a Florida town has a life-size statue of one of the flight attendants killed; a bench and flagpole on the Atlantic City boardwalk honor another victim.
On a larger scale, plans for the Flight 93 National Memorial were unveiled last week, a tribute to the passengers who forced down a hijacked plane in Pennsylvania; it includes a 93-foot Tower of Voices. The memorial design for the Pentagon features 184 illuminated benches, one for each victim.
There are parallels here, too, with Pearl Harbor.
"What do people do when they go to Hawaii? They go to Pearl Harbor and visit the USS Arizona," Laderman said.
"It became a strange kind of pilgrimage spot, a tourist spot. And that seems to be happening with September 11 and Ground Zero," he said. "But it also seems very much in line with American culture. Even if it is turned into a holiday, maybe September 11, over the years, will be about a place, and not a time."