In the middle of a vast stretch of grassland in western Pennsylvania, poet Robert Pinsky read out 40 names to a somber and silent crowd. After the poet said each name, two large bells were chimed.

Former presidents, state officials, bereaved relatives, artists and members of the public gathered Saturday to open a 1,500-acre national park on the outskirts of Shanksville, in honor of the 40 passengers and crew members who died on United Airlines Flight 93 on Sept. 11, 2001.

“With their brave decision they launched the first counteroffensive in the war on terror,” former president George W. Bush said. “Americans are alive today because the passengers and crew of Flight 93 chose to act, and we will forever be grateful.”

The other three planes hijacked by al-Qaeda on that day hit their high-profile targets: the World Trade Center and the Pentagon. But the people aboard Flight 93, which left Newark for San Francisco before hijackers turned it around, realized what was happening and revolted against their four assailants. A plane now thought to have been heading for the Capitol or the White House instead crashed in an anonymous field. No one on the ground was killed.

The National Park Service has spent $52 million on the new park, with $32 million in public funding and $20 million in private funding. The unveiling of a marble wall engraved with the 40 names marked the climax of Saturday’s ceremony. The wall is aligned with the path of the plane as it crashed.

However, 10 years on, the park is unfinished.

“I was aghast to find out that you still need $10 million to build this place,” said former president Bill Clinton, addressing the crowd. Some clutched umbrellas decorated with stars and stripes, in case this week’s rains returned to disrupt the clear and sunny afternoon.

Clinton pledged to hold a bipartisan fundraising event in Washington to “get this show on the road.” The extra $10 million is required for features such as a visitors center. The Park Service also hopes to buy an additional 700 acres to protect views of the park.

More than 1 million people have visited the crash site in the past 10 years. A 40-foot chain fence, where visitors hung offerings such as handwritten messages and bottles of holy water, was used as a temporary memorial.

The bereaved family members said the expansive new memorial was a fitting tribute to their loss. They hoped the extra funding could be found quickly despite the belt-tightening across government and households.

“It would [add] an insult to the injury already suffered if this didn’t happen, didn’t get funded and built as quickly as possible,” said Patrick White, a 59-year-old lawyer from Naples, Fla., whose cousin died in the crash. “If we can put a man on the moon . . . then we can build a memorial.”

Some people traveled from nearby states; others had made special detours during road trips.

“Those people gave their lives,” said David Gebert, a flight attendant from San Francisco who had made sure that his drive to the East Coast would include a stop at the park’s opening ceremony. “I work in the industry, so it means even more to me.”

But there is less enthusiasm for the project among some residents of Shanksville, a town of just 237 people that was plucked from obscurity after the plane crash on its doorstep.

Many residents volunteer at the temporary memorial and deeply respect the need to commemorate the passengers and crew on Flight 93. Yet they are unsure whether so much money — $18 million of which came from state funds — and so much local land should have been put toward the cause, especially when the folksy chain fence had proved popular and imaginative.

“The locals are surprised that I’m coming to the dedication,” said Ernie Stotler, 71, a retired psychologist who was born in Somerset County and lives a quarter mile from the memorial site. “I have four brothers and a sister who live within five miles of where we’re standing now, and they’re not coming. . . . They all think it’s overdone.”

“But I think this is fitting. If we are going to continue to survive as a great nation, we have to value people like’’ those on Flight 93, Stotler said.