Americans commemorated 9/11 on Friday as a new national crisis — the coronavirus pandemic — reconfigured anniversary ceremonies and a presidential campaign carved a path through the observances.

President Donald Trump marked the 19th anniversary with a patriotic message for the world: “No matter the threat. No matter the odds. America will always rise up, stand tall and fight back.”

Trump delivered a sobering speech in rural Shanksville, Pennsylvania, where Flight 93, hijacked by terrorists, crashed in a field, killing all 40 aboard. Former Vice President Joe Biden is to visit Shanksville later Friday after attending the 9/11 Memorial & Museum’s annual commemoration at ground zero in New York.

“To the family members of Flight 93, today every heartbeat in America is wedded to yours,” Trump said. “Your pain and anguish is the shared grief of our whole nation. ... While we cannot erase your pain, we can help to shoulder your burden.”

Trump also noted that America came together after 9/11.

“It was a unity based on love for our families, care for our neighbors, loyalty to our fellow citizens, pride in our great flag, gratitude for our police and first responders, faith in God and a refusal to bend our will to the depraved forces of violence, intimidation, oppression and evil.”

In New York, victims' relatives gathered Friday morning for split-screen remembrances, one at the Sept. 11 memorial plaza at the World Trade Center and another on a nearby corner, set up by a separate 9/11-related organization.

The Stephen Siller Tunnel to Towers Foundation objected to the memorial’s decision to forgo a longstanding tradition of having relatives read the names of the dead, often adding poignant tributes. Memorial leaders said they made the change as a coronavirus-safety precaution on the 19th anniversary of the deadliest terror attack on U.S. soil.

The new York City police department has released aerial photographs its officers took on the attack on the World Trade center on September 11 2001. (AP/Feb. 10)

Meanwhile, Vice President Mike Pence is also due at ground zero — and then at the alternate ceremony a few blocks away.

In short, the anniversary of 9/11 is a complicated occasion in a maelstrom of a year, as the U.S. grapples with a health crisis, protests over racial injustice and prepares to choose a leader to chart a path forward.

Still, 9/11 families say it’s important for the nation to pause and remember the hijacked-plane attacks that killed nearly 3,000 people at the trade center, at the Pentagon and near Shanksville on Sept. 11, 2001, shaping American policy, perceptions of safety and daily life in places from airports to office buildings.

“I know that the heart of America beats on 9/11 and, of course, thinks about that tragic day. I don’t think that people forget,” says Anthoula Katsimatides, who lost her brother John and is now on the board of the National Sept. 11 Memorial & Museum.

Sites of 9/11 Then and Now

Friday will mark Trump’s second time observing the 9/11 anniversary at the Flight 93 memorial, where he made remarks in 2018. Biden spoke at the memorial’s dedication in 2011, when he was vice president.

The ground zero ceremony in New York has a longstanding custom of not allowing politicians to speak, though they can attend. Biden did so as vice president in 2010, and Trump as a candidate in 2016.

Though the candidates will be focused on the commemorations, the political significance of their focus on Shanksville is hard to ignore: Pennsylvania is a must-win state for both. Trump won it by less than a percentage point in 2016.

WATCH: Eagle Lands On Top Of Firetruck Ladder During 9/11 Memorial

Around the country, some communities have canceled 9/11 commemorations because of the pandemic, while others are going ahead, sometimes with modifications.

The New York memorial is changing one of its ceremony’s central traditions: having relatives read the names of the dead, often adding poignant tributes.

Thousands of family members are still invited. But they’ll hear a recording of the names from speakers spread around the vast plaza, a plan that memorial leaders felt would avoid close contact at a stage but still allow families to remember their loved ones at the place where they died.

Over a Dozen Men Near Ground Zero After 9/11 Have Breast Cancer Jeffrey Flynn spent months around Ground Zero after 9/11 and has been diagnosed with Stage 3 breast cancer. He received a six-figure award from the September 11th Victim Compensation Fund, Michael Barasch, Jeffrey Flynn’s attorney, via ABC11 Michael Barasch, via ABC11 Barasch recommends everyone who was near ground zero get checked for breast cancer Jeffrey Flynn, via ABC11

But some victims' relatives felt the change robbed the observance of its emotional impact. A different 9/11-related group, the Stephen Siller Tunnel to Towers Foundation, set up its own, simultaneous ceremony a few blocks away, saying there’s no reason that people can’t recite names while keeping a safe distance.

The two organizations also tussled over the Tribute in Light, a pair of powerful beams that shine into the night sky near the trade center and evoke its fallen twin towers. The 9/11 memorial initially canceled the display, citing virus-safety concerns for the installation crew. After the Tunnel to Towers Foundation vowed to put up the lights instead, the memorial changed course with help from its chairman, former Mayor Mike Bloomberg, and Gov. Andrew Cuomo.

Tunnel to Towers, meanwhile, arranged to display single beams for the first time at the Shanksville memorial and the Pentagon.

Over the years, the anniversary also has become a day for volunteering. Because of the pandemic, the 9/11 National Day of Service and Remembrance organization is encouraging people this year to make donations or take other actions that can be accomplished at home.