With solemn ceremonies and prayers, moments of silence and the ringing of bells, the nation on Sunday marked the 15th anniversary of the Sept. 11 terrorist attacks that claimed the lives of 2,977 victims and forever changed how the United States views itself and its place in the world.
Commemorations unfolded in New York and outside Washington, where hijackers piloted planes into the World Trade Center and Pentagon, and in a rural field in Pennsylvania, where Flight 93 crashed after passengers fought back against their hijackers.
“As Americans, we do not give in to fear,” President Obama said at the Pentagon Memorial service, as about 800 family and friends of those who died stood for 30 seconds of silence at 9:37 a.m. Eastern, the same time of morning that a jetliner struck the building and killed 184 people.
Democratic presidential nominee Hillary Clinton and Republican nominee Donald Trump attended the ceremony in Lower Manhattan, but Clinton left early, and appeared to stumble as she approached her vehicle. She was helped by Secret Service agents.
A statement from campaign spokesman Nick Merrill said Clinton had felt overheated on the warm, humid morning. The campaign later issued a statement from Clinton’s doctor saying she had been diagnosed with pneumonia on Friday and was recovering from it.
After leaving the memorial, she went to daughter Chelsea’s apartment to rest and emerged about two hours later, smiling and appearing healthy. "It's a beautiful day in New York," she said as she left.
Asked if she was feeling better, she replied: “Yes, thank you very much.”
The New York ceremony started with a moment of silence at 8:46 a.m. Eastern, coinciding with the time the first plane struck the north tower. Some bowed their heads while others held high the photos of their loved ones.
Then began the lengthy process of reading out the names of the victims. Family members came to the stage in pairs to read them out and sometimes add a heartfelt message about the victims.
Jeremy D'Amadeo said he was 10 when his father, Vincent, was killed at the World Trade Center, and he spent many summers at a camp for children of 9/11 victims.
"This summer I had the privilege of working with kids who had their own tragic loss, kids of Sandy Hook," D'Amadeo said, referring to the elementary school in Newtown, Conn., where 20 children and six adults were killed by a gunman in 2012. "These kids lifted me up and made me know that I wanted to give back as much as I can."
He added: "Sometimes the bad things that happen in our lives put us on the paths we should be going, to help others as much as we can. P.S.: Dad, I love you."
Emily Ortiz, 16, of Queens, said she found comfort in attending the anniversary ceremony because it allowed her to remember her father, Pete Ortiz, who died on 9/11. She said he worked on the 92nd floor of the north tower.
"We've always heard stories of my father, so this is another way to feel closer to him," Ortiz said.
Dennis Scauso was one of 343 New York City firefighters who died trying to save people at the World Trade Center; his remains were never found. His relatives came to the ceremony as they do every year, finding comfort in the company of others who lost loved ones in the attack.
"It's all very beautiful because you are surrounded by people who are going through and feeling the same thing you are going through," said one of his sisters, Nancy Shakouri. "We can't imagine being anywhere else on this day."
Scauso was 46 when he died. He had been called in on his day off to join the other members of his hazmat unit at Ground Zero. In all, 19 firefighters in his unit died that day, his family said.
The New York remembrance was a private event attended by families and local officials.
At the ceremony at the Pentagon in Arlington, Va., a large American flag hung from the roof of the building where American Airlines Flight 77 barreled into the limestone facade of the building. It billowed in gusts of wind that moved streaks of clouds across the pale blue sky, occasionally blocking out the sun.
Defense Secretary Ashton Carter and Chairman of the Joint Chiefs of Staff Gen. Joseph F. Dunford Jr. joined Obama in placing a wreath of white lilies in the memorial garden, and a military band played "America the Beautiful."
"The most enduring memorial... is ensuring the America we continue to be, that we stay true to ourselves, stay true to what is best in us, that we not let others divide us," the president said.
Several hundred families and friends of those who died participated in Sunday’s memorial, many wearing red white and blue ribbons in their lapels. A few young boys wore ironed white shirts, their hair neatly parted and combed into place for the morning.
A girl, about 6 years old, in a blue and white striped dress, held a single yellow chrysanthemum and followed her family through the memorial garden to place the flower on one of184 curved benches spaced between crape myrtle trees. A narrow channel of rippling water reflected light below them.
"There are a million places I’d rather be than at the Pentagon" on Sept. 11, said Devora Kirschner, 40, whose husband was working as a Naval intelligence officer the day he was killed in the attack.
As she spoke, a jetliner flew past the building, taking off from Reagan National Airport nearby. "Especially with planes flying overhead," she said, standing next to her husband's bench. "It's unnerving."
Four years ago, Kirschner got remarried. She wanted to attend Sunday's service to place flowers, a bouquet of sunflowers and roses, on the memorial bench that bears the name of her late husband, Lt. Darrin H. Pontell.
A friend of her husband's had placed a CD by the band Rush, her husband's favorite. "I look at the benches that don't have flowers. I would hate it if my husband didn't have flowers," Kirschner said.
Abraham Scott, 64, came to the Pentagon with his two daughters, two granddaughters and many other relatives and friends.
His wife, Janice Marie Scott, was working as a budget officer at the Pentagon on the morning of the attack.
For years, Scott sat in monthly therapy sessions with other families of people killed at the Pentagon. He talked about his wife's death and how it upended his family's life, how she had sorted her personal files at home the weekend before she died, almost as if she had a premonition she would be taken from them.
"My desire to hate has gone," Scott said. "I turned hatred into a means to keep their memory alive.”
Over the last several years, Scott has worked with other family members who lost loved ones on Sept. 11 to push the federal government to adopt the recommendations of the 9/11 Commission. He lobbied lawmakers to pass a law that would strip sovereign immunity from countries believed to support terrorism, opening up the ability for victims of terror attacks to sue countries that may have helped carry out an attack.
That bill, called the Justice Against Sponsors of Terrorism Act, was already approved by the Senate and passed the House on Friday. The bill will be sent to the White House for President Obama's signature in the coming days. Obama has been reluctant to support the bill because other countries could adopt similar policies that would open the U.S. government up to a raft of new liabilities and lawsuits for its actions overseas.
At the Flight 93 National Memorial in southwestern Pennsylvania, the ceremony included music, the reading of the names of the 40 victims who died there and the ringing of bells.
With the anniversary falling on a Sunday, the National Football League also held observances, including a recorded video message from Obama.
Vice President Joe Biden participated in a pregame National Anthem ceremony in Philadelphia before the Eagles’ game against the Cleveland Browns. Former President George W. Bush and his wife, Laura Bush, appeared at the Cowboys-New York Giants game in Dallas.
Many smaller tributes were scheduled around the country on a day that has become a time of national mourning.
Among them was the 9/11 Memorial Stair Climb in Austin, Texas, where firefighters, in full gear, climb up and down the Pleasant Valley Drill Tower enough times to roughly equal the height of the original World Trade Center towers.
In Los Angeles, a Muslim organization was holding its sixth annual Sept. 11 blood drive. "As Muslims, our message is simple: We don't shed blood, we give blood," said an emailed statement from Dr. Ahsan Khan, president of Ahmadiyya Muslim Community’s Los Angeles chapter.
Across the New York harbor from Manhattan, an afternoon ceremony was being held at New Jersey's Empty Sky Memorial in Liberty State Park to honor the state’s 749 residents who died on Sept. 11.
And in Manhattan, tourists crowded the memorial fountains built into the footprints of the two original World Trade Center towers.
Some people left individual white roses and miniature American flags on the fountains’ black granite edges, where the names of victims are engraved.
Among the visitors was Greg Brierley, 49, of Milan, Mich., a retired firefighter who said he came to the site to remember the first responders killed on Sept. 11. “We’re all brothers and sisters,” he said.
Haller, a special correspondent, reported from New York, and Bennett reported from Arlington, Va.