For the Flight 93 families, the most touching aspect of Saturday's dedication of a national memorial to their loved ones wasn't the speechmaking or musical tributes.

It was the crowd.

Perhaps a thousand ordinary Americans -- no one was keeping official count -- turned out to join them on the eve of the 10th anniversary of the September 11 attacks and to let them know that they, too, are not forgotten.

With no prompting, they broke into applause as they solemnly departed the 2-1/2 hour ceremony along an elongated black asphalt walkway that sweeps past the daisy-dotted spot where the hijacked Boeing 757 went down.

"It's an emotional day. It's overwhelming to see everyone here," said Gordon Hasenei, whose aunt, retiree Patricia Cushing, boarded the ill-fated United Airlines flight in Boston for a holiday in San Francisco.

"This makes me proud to be an American," added Reverend Kenneth Mills, uncle of United flight attendant CeeCee Ross Lyles and one of few African-Americans present, with unabashed patriotism.

Organisers sealed off a seated section for the Flight 93 families in front of the shaded dias where former presidents George W. Bush and Bill Clinton reaffirmed US determination to defeat global terrorism.

The general public -- predominantly from this rural corner of Pennsylvania, a traditional American landscape of small farms, tidy villages and sweeping hills -- unfolded leisure chairs in the muddy soil around the perimeter.

Many sported patriotic T-shirts and held American flags. Nobody flinched when a giant screen that was supposed to project the goings-on on stage blew a circuit and went blank, sending a puff of smoke into the air.

Some applauded when Bush took to the stage, but Clinton gave the more impassioned speech, saying that by rising up against the hijackers, the passengers and crew of Flight 93 had denied Al-Qaeda "a symbolic victory."

It is believed the hijackers intended to plow Flight 93 into the Capitol building in Washington, about 20 minutes' flying time from Shanksville, just as their cohorts did earlier that day at the World Trade Center and the Pentagon.

Alice Hoagland, who lost her PR executive son Mark Bingham, comes to Shanksville every September 11, but this year she opted not to trek across the rain-soaked field to the spot where Flight 93 slammed into the ground.

Instead, for the first time, she touched a tall, finely polished and newly installed granite tablet bearing Bingham's name -- identical to the 39 others lined up along Flight 93's final flight path as a key part of the memorial.

"It's a healing process and I expect to go through it through the rest of my life," Bingham told AFP afterwards.

Several airline pilots in uniform turned out as well, including Chris Clark of Delta Airlines, a friend of Flight 93's first officer LeRoy Homer from their days together flying cargo planes in the US air force.

Does Clark worry about another 9/11-style hijacking when he steps in the cockpit? No, he replied. "I feel something like this won't happen again. They" -- meaning Al-Qaeda -- "have played their card."