NEW YORK—Delivered in voices strong and soft, steady and shaky, the 2,792 names kept coming. For two and a half hours, they echoed across the dusty desolation at Ground Zero, conveyed from the lips of children, who—whatever their age—seemed much too young to read the long and heartbreaking roll call of their dead.

But, somehow, they did it.

Often punctuated with a tender “I love you, daddy” or “We love you, mommy,” their wrenching recitations provided some of the most poignant moments as the nation and the world marked the second anniversary of the Sept. 11, 2001, terrorist attacks on the World Trade Center and the Pentagon.

In Washington, on the South Lawn of the White House, President Bush and his staff stood with heads bowed in silence at 8:46 a.m. EDT, the time the first hijacked jet, American Airlines Flight 11, plowed into the north tower of the trade center.

British Prime Minister Tony Blair and his Cabinet observed the same moment of silence in London, as did U.S. troops in Baghdad, fire-fighters in Chicago and suburban-ites in Middletown, N.J., which lost 37 residents that day.

Across the nation, flags flew at half-staff and church bells tolled in recognition of the worst terrorist attack in the nation's history. At the Pentagon, a tone sounded at 9:37 a.m. EDT and 20,000 military and civilian workers stopped in their tracks to stand in silent recognition of the moment when American Airlines Flight 77 sliced into the building, killing 184 people.

Defense Secretary Donald Rumsfeld laid a wreath at Arlington National Cemetery in memory of the 3,016 people killed in New York, Washington and aboard the hijacked United Airlines flight that crashed in a field outside Shanksville, Pa.

Like observances elsewhere in the country, New York's commemoration took a far more muted tone than it had a year ago. It began with a three-hour ceremony at Ground Zero in the morning and ended with the sunset appearance of two columns of light, replicating the shape of the former twin towers, that will fade at sunrise Friday.

The morning ceremony centered around the theme of children, who performed all of the music and read all of the names of those who died in south Manhattan that day.

Before the reading of the names began at 8:49 a.m., a children's choir sang a sweet, high-pitched rendition of “The Star-Spangled Banner.”

Then Peter Negron, 13, came to the podium and shyly recited a poem in honor of his father, Pete, 34, who worked as an environmental project manager for the Port Authority, the owner of the trade center. Titled “Stars,” the poem ended, “I felt them watching over me, each one—and let me cry and cry till I was done.”

New York City Mayor Michael Bloomberg introduced the reading of the names with a short poem called “The Names” by former U.S. poet laureate Billy Collins, which ended with “Names wheeled into the dim warehouse of memory. So many names, there is barely room on the walls of the heart.”

Tears flowed freely among the hundreds of gathered families and friends when, two by two, 200 young relatives took turns reciting a litany of loss that included parents and grandparents, aunts and uncles, stepparents and godparents, brothers and sisters and cousins.

Among the youngest readers was Jessica Murphy, 7, whose father Brian, 41, was a vice president for the investment firm of Cantor Fitzgerald. Among the oldest was Liliana Cabezas Dorado, 38, whose father, Jesus Cabezas, 60, worked as a cook at Windows on the World, the famed restaurant on the top of the north tower. But most of the readers were teen-agers.

Sometimes they wept as they read. Sometimes they smiled bravely. Sometimes they struggled with difficult-to-pronounce names, and there were many of those, reflecting the dozens of nationalities and ethnic groups represented by those who died.

But always, they ended their recitations with the names of their own lost loved ones. And often, they would add “I love you, daddy,” as did Gemma Alviar, 21, whose father Cesar, 60, was an accountant with Marsh & McLennan. Or, “We love you, mommy,” as Nicholas Chirls, 18, and his 12-year-old sister, Sydney, said of their mother, Catherine, 47, a financial worker with Cantor Fitzgerald.

Readings, beyond those of the names, were brief and elegantly appropriate. Drawing from Stephen Spender's poem “I Think Continually of Those Who Were Truly Great,” New York Gov. George Pataki intoned: “The names of those who in their lives fought for life, Who wore at their hearts the fire's centre.”

New Jersey Gov. Jim McGreevey quoted Eleanor Roosevelt's belief that “we do not have to become heroes overnight. Just a step at a time, meeting each thing that comes up, discovering we have the strength to stare it down.”

Former New York Mayor Rudolph Giuliani, who led the city through the crisis, offered inspiration in Winston Churchill's bracing exhortation to “repair the waste. Rebuild the ruins. Heal the wounds. … Let us go forward together.”

And Joan Molinaro, who lost her firefighter son Carl, 32, read a heartrending poem of her own. It ended with the words, “My baby boy is gone.”

Family members said the most moving moment of the ceremony was hearing the name of their own loved one read aloud.

“A lot of people don't have anything other than this spot and the moment the name is read,” said Elizabeth Mendez, whose cousin, Edward Calderon, was one of the 84 Port Authority employees who died. “That's their only memorial.”

As the readings continued, a steady stream of families and friends walked up and down the ramp to the stony dirt floor of the pit, 70 feet below street level.

Most of them carried yellow and red roses, small American flags, photos and other mementos to lay on memorial piles that grew higher as the morning wore on.

Many wore pictures of their lost ones on buttons or T-shirts, others carried bouquets of balloons with names inscribed on them. Some stood still and silent on the tawny, dusty ground. Some sat down on it, often children cradled in their arms. Some held up large poster-sized photos of their dead. Others lit candles for them.

One woman scraped at the hard ground to carve a message; another arranged pebbles to spell out a name. One wrote a name with pink rose petals. And many people scooped up handfuls of dirt to take home, sometimes pouring it into whatever they had at hand: empty foil snack bags or plastic water bottles.

A group of firefighters in dress uniform gathered for a group photo around a commemorative wreath of carnations. A knot of family members huddled, heads together and arms wrapped around each other, their lips moving in prayer.

The Red Cross handed out tissues.

“It's horrifying to be there, but it's healing in a way,” said Barry Zelman, 48, whose brother Kenneth, 36, worked at the insurance services firm Marsh & McLennan. “It's where my brother was murdered, so it's where I have to be every Sept. 11.”

Maura Landry, 25, whose fiance, Matthew Horning, died in the north tower, said the mood among family members who descended to the bottom of Ground Zero was noticeably different from last year.

“It was not just 100% focusing on their deaths but also on the people and who they were,” Landry said. “You'd see people laughing a little bit as they remembered something funny about a person. That's not to say there weren't people who didn't sit on the ground and cry the whole time.”

Still, some said they are haunted by nightmares of that day. Harry Halvorsen, 56, a technician for telecommunications provider MCI, said he was working on the 83rd floor in the trade center's south tower when the first plane struck the north tower. He escaped and later joined rescue efforts at ground zero.

But he has a recurring nightmare: “I'm still looking for the other half of a woman I found. I found the lower half. I'm still looking for the upper half.”

The feelings engendered by the tragedy and the heroism that took place two years ago extended far beyond New York on Thursday.

On Chicago's West Side, more than 1,000 students from Hanson Park Elementary School, including 225 physically disabled children, gathered for a commemorative assembly. Anna Winchell, 14, who is physically disabled, recalled hearing about a disabled man who couldn't escape from one of the top floors of the World Trade Center.

“Somebody actually stayed up with [the] disabled man and he didn't go down. He died with him,” she said, referring to Abraham Zelmanowitz, who stayed with his paraplegic friend Edward Beyea. “It's good to remember these kinds of things, how many people sacrificed themselves.”