Americans remembered 9/11 on Sunday with tear-choked tributes and pleas to "never forget," 21 years after the deadliest terror attack on U.S. soil.

"It's been 21 years, but it's not 21 years for us. It seems like just yesterday," she said before reading victims' names at the World Trade Center to a crowd that included Vice President Kamala Harris and husband Doug Emhoff.

At the Pentagon, which also was targeted on 9/11, President Joe Biden vowed that the U.S. would continue working to root out terrorist plots and called on Americans to stand up for "the very democracy that guarantees the right to freedom that those terrorists on 9/11 sought to bury in the burning fire, smoke and ash.

" First lady Jill Biden spoke at the third attack site, a field near Shanksville, Pennsylvania.

The attacks killed nearly 3,000 people, reconfigured national security policy and spurred a U.S. "war on terror" worldwide.

Pierre Roldan, who lost his cousin Carlos Lillo, a paramedic, said "we had some form of justice" when a U.S. raid killed Osama bin Laden in 2011.

The Sept. 11 attacks stirred — for a time — a sense of national pride and unity for many, while also subjecting Muslim Americans to years of suspicion and bigotry and engendering debate over the balance between safety and civil liberties. In ways both subtle and plain, the aftermath of 9/11 ripples through American politics and public life to this day.

"It was a terrorist attack against our country that day. And theoretically, everybody should remember it and, you know, take precautions and watch out," said Saloman, who lost his brother, Wayne Saloman.

"I'm here today to represent generation 9/12, those who never experienced 9/11 but still suffer the aftermath of it," Walsh-DiMarzio said. "We will never, ever forget."