Like 2001, this Sept. 11 was on a Tuesday, for the second time since the attacks. The early fall weather was much like the morning on 2001.
Mayor Michael Bloomberg, the governors of New York and new Jersey and former Mayor Rudy Giuliani all attended New York's ceremony. Biden spoke to hundreds at the Flight 93 Memorial in Pennsylvania, saying the ceremonies were a reminder that the country hasn't forgotten them.
The Obamas planned later to visit wounded soldiers at Walter Reed Army Medical Center. The U.S. terror attacks were followed by wars in Afghanistan and Iraq, where the U.S. military death toll years ago surpassed the 9/11 victim count. At least 1,987 U.S. troops have died in Afghanistan and 4,475 in Iraq, according to the Pentagon.
Allied military forces marked the anniversary at a short ceremony at NATO's headquarters in Kabul, Afghanistan with a tribute to more than 3,000 foreign troops killed in the decade-long war.
"Eleven years on from that day there should be no doubt that our dedication to this commitment, that commitment that was seared into our souls that day so long ago, remains strong and unshaken," said Marine Gen. John Allen, the top commander of U.S. and coalition troops.
Other ceremonies were held across the country — from New York's Long Island, where hundreds wrote messages to their loved ones on a memorial, to Boston, where more than 200 people with ties to Massachusetts were remembered. But some cities scaled back — Middletown, N.J., which lost 37 residents, held a small, silent ceremony instead of previous events with speeches and music. The New York City suburb of Glen Rock, N.J., where 11 people were killed, did not hold a memorial this year for the first time.
"It was appropriate for this year — not that the losses will ever be forgotten," said Brad Jordan, chairman of a Glen Rock community group that helps victims' families. "But we felt it was right to shift the balance a bit from the observance of loss to a commemoration of how the community came together to heal."
The anniversary led to a brief pause in the presidential campaign as Obama and Republican challenger Mitt Romney pulled their negative ads and avoided campaign rallies. Romney shook hands with firefighters at Chicago's O'Hare Airport and was flying to Nevada to address the National Guard, whose members deployed after the attacks. His running mate, Rep. Paul Ryan of Wisconsin, had no scheduled public events.
The memorial foundation announced this summer that politicians wouldn't be included this year, to separate politics from the ceremony. But others said keeping elected officials off the rostrum smacked of ... politics. And several said they were unwilling to let go.
"Coming here, it's like ripping off a Band-Aid," said Yasmin Leon, whose sister was killed at the trade center. "You rip it off and the wound is opened again. But you keep coming back anyway."
And at ground zero, family members reading their loved ones' names said the passage of time did not change their grief.
"Mark, they say time heals all wounds. It's not true, Mark," said Joanne Hindy, whose nephew died in the north tower. "There's a void in all our lives because this that will never ever be filled or healed."
Associated Press writers Verena Dobnik, Meghan Barr and Alex Katz in New York, Wayne Parry in Atlantic City, N.J., Steven R. Hurst in Washington, Joe Mandak in Shanksville, Pa., and Amir Shah in Afghanistan contributed to this report.
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