WATCH: US commemorates 9/11 victims at ceremonies at Pentagon and crash site in Pennsylvania

NEW YORK (AP) — The United States remembered the lives lost and changed by Sept. 11, marking an anniversary marked by campaign-driven political activity, as President Joe Biden, former President Donald Trump and Vice President Kamala Harris stood together at Ground Zero on Wednesday.

September 11 – the date on which nearly 3,000 people were killed in hijackings in 2001 – comes at the height of the presidential election every four years, and this time the timing is particularly crucial. At the anniversary ceremony at the World Trade Center, Harris and Trump, the Democratic and Republican candidates, met in person just hours after their first-ever debate on Tuesday night.

Trump and his running mate, Senator JD Vance, arrived at the World Trade Center around 8 a.m. and posed for photos with some onlookers. Harris arrived with Biden about half an hour later, as some onlookers chanted “Kamala!”

Biden and Trump shook hands, and former New York Mayor Michael Bloomberg appeared to broker a handshake between Harris and Trump. Then the two presidential rivals stood just feet apart, with Biden and Bloomberg between them, as the service began with the ringing of a bell and a moment of silence.

Former President Donald Trump shakes hands with Vice President Kamala Harris during a ceremony marking the 23rd anniversary of the September 11, 2001 attacks on the World Trade Center at the 9/11 Memorial and Museum in Manhattan. Photo by Mike Segar/ Reuters

For relatives of the victims, such as Cathy Naughton, who came to pay her last respects to her cousin Michael Roberts, one of the hundreds of firefighters killed in the attack, the political background was not a major issue.

Twenty-three years later, “it’s just so awesome,” she said. “We want to make sure people always remember, always say the names and never forget.”

“It just doesn’t get any easier every year,” she added.

Regardless of the campaign calendar, memorial organizers have long sought to focus on the victims. For years, politicians have been mere observers at Ground Zero memorials, with the microphone instead taken over by relatives who read the victims’ names aloud.

If politicians “are interested in what’s really going on, that’s great. Then they’re here,” said Korryn Bishop, who lost her cousin John F. McDowell Jr. “If they’re just here for their political influence, that annoys me.”

Biden, the last 9/11 of his term and likely his 50-year political career, was later scheduled to join Harris for ceremonies in Pennsylvania and at the Pentagon, the three sites where commercial airliners crashed on Sept. 11, 2001, after being taken over by al-Qaeda members. Trump was also scheduled to appear at the Flight 93 National Memorial near rural Shanksville, Pennsylvania.

Biden and Harris are expected to lay a wreath at the crash site of Flight 93. Watch the video below.

Officials later concluded that the plane that crashed there was en route to Washington. It crashed after crew members and passengers attempted to wrest control from the hijackers.

The attacks killed 2,977 people, left thousands of relatives dead, and injured many survivors. The planes left a scar on the Pentagon, the headquarters of the US military, and brought down the twin towers of the World Trade Center, which were among the tallest buildings in the world.

The disaster also changed U.S. foreign policy, domestic security practices, and the mindset of many Americans who had previously felt at risk from attacks by foreign extremists.

The consequences were felt around the world and for generations to come, as the United States responded with a “global war on terrorism,” which included invasions of Afghanistan and Iraq. These operations killed hundreds of thousands of Afghans and Iraqis, as well as thousands of American soldiers, and Afghanistan became the site of the United States’ longest war.

As the complex legacy of 9/11 continues to evolve, communities across the country have developed memorial traditions ranging from wreath-laying to flag-raising, from protest marches to police radio calls, and volunteer projects to mark the anniversary, which Congress has designated as both Patriot Day and a National Day of Service and Remembrance.

Biden and Harris are expected to lay a wreath at the Pentagon at 5 p.m. EDT. Watch live below.

At Ground Zero, presidents and other officials read poems, portions of the Declaration of Independence, and other texts during the first anniversaries.

But that ended after the National Sept. 11 Memorial and Museum decided in 2012 to limit the ceremony to relatives reading the names of the victims. Bloomberg was chairman at the time and still is.

Politicians and candidates were still able to attend the event, and many did so, particularly New Yorkers who were in office during the attacks, such as former Secretary of State Hillary Clinton, who was then a U.S. senator.

She and Trump met at the 9/11 memorial service at Ground Zero in 2016, and this became a sensitive chapter in the presidential campaign at the time.

Clinton, then the Democratic nominee, abruptly left the ceremony, stumbling while waiting for her motorcade and later announcing that she had been diagnosed with pneumonia a few days earlier. The incident drew renewed attention to her health, which Trump had questioned for months.

In 2008, then-Senators and presidential rivals John McCain and Barack Obama made a visible effort to keep politics out of the anniversary, visiting Ground Zero together to pay their respects and lay flowers in a reflecting pool that was then a pit.

Certainly, family members of victims occasionally send their own political messages at the ceremony, and readers generally make brief remarks after completing the names assigned to them.

Some of their relatives have used the forum to lament the divisions in American society, call on politicians to make national security a top priority, recognize the victims of the war on terror, complain that politicians are politicizing 9/11 and even criticize individual officials.

But most readers limit themselves to tributes and personal reflections, increasingly from children and young adults who were born after a parent, grandparent, aunt or uncle was killed in the attacks.

—Jennifer Peltz and Karen Matthews, Associated Press

Associated Press journalists Julie Walker and Adriana Gomez Licon contributed.