HARRISBURG, Pa. — Serene, stark and seemingly in the middle of nowhere in Pennsylvania, the National Park Service memorial to the people who died on United Airlines Flight 93 is hard to find on a map — as the Sept, 11, 2001, terrorist attack itself slips deeper into the nation’s collective memory.

And even schools that do teach about the day may only bring it up only on the anniversary, rather than as a point in a long arc of history and a turning point that left the U.S. irrevocably changed, 20 years later.

Families of Flight 93’s 40 passengers and crew members are trying something new to change that: an annual award for heroism. Nominations opened Monday through the nonprofit group, Friends of Flight 93 National Memorial.

The award aims to reward selfless acts of heroism, but also to educate the public on what happened when those aboard the hijacked plane, bound for San Francisco, discovered that jets had been flown into the World Trade Center towers in New York and the Pentagon outside Washington.

The passengers and crew of Flight 93 then tried to wrest control of the aircraft, which crashed into a field, leaving no survivors — a sacrifice then-President George W. Bush called one of the most courageous acts in U.S. history, believed to have stopped a catastrophic crash into the White House or the Capitol.

The hope is to use the award to connect teachers to the Friends’ organization’s considerable teaching materials and historical records from the day, and bring it to classrooms, said Donna Gibson, a banking executive who, as president of the Friends organization, has given countless tours of the site tucked amid the wildflowers in Pennsylvania’s Laurel Highlands.

By the time the 20th anniversary rolls around in four months, 75 million Americans will have been born in those two decades, the organization estimates.

“One of the questions I get when people visit is, ‘Was this a national park when the plane crashed here?’ ” Gibson said.

The families of Flight 93 victims also worry that the Flight 93 story is overshadowed by the stories of the planes that crashed into the World Trade Center and the Pentagon.

Those memorials in New York and Washington — major urban centers, as opposed to a rural field — might pull in millions of visitors a year.

The Flight 93 memorial attracted 411,000 visitors in 2019, according to National Park Service figures.

But it is also a click away online, with resources for teaching about Flight 93 and Sept. 11.

“The award is for things that were done in 2020, but how that ties back to 9/11 and Flight 93 and the resources that we have,” said Emily Schenkel, a Bethlehem, Pa., resident whose godmother was an attendant on Flight 93. “So this is keeping that awareness and making these connections for younger people who either weren’t alive or don’t have a recollection of 9/11.”