Americans marked the 14th anniversary of the Sept. 11 attacks in countless ceremonies, small and large, on Friday. Governors ordered flags flown at half-staff. Military commanders laid wreaths and servicemen fired 21-gun salutes. Here is a look at some notable commemorations:

SHANKSVILLE, PENNSYLVANIA

Hundreds of people, including Homeland Security Secretary Jeh Johnson, gathered at the memorial park in western Pennsylvania where United Airlines Flight 93 was brought down by hijackers. This year's ceremony took place outside a new $26 million visitor center honoring the slain passengers and crew. It was dedicated Tuesday.

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WASHINGTON

President Barack Obama and first lady Michelle Obama observed a moment of silence at 8:46 a.m. with hundreds of White House employees and administration staff. A bugler played taps. Across the Potomac River, Defense Secretary Ash Carter attended a wreath ceremony at the Pentagon where 184 people died.

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BOSTON

A wreath was laid at the 9/11 memorial in Boston's Public Garden and the names of 200 attack victims with ties to Massachusetts were read during a ceremony inside the state capitol building. Officials presented a civilian bravery award named for Madeline Amy Sweeney, a flight attendant aboard hijacked American Airlines Flight 11, to a livery driver who grabbed a gun from a kidnapping suspect.

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THE PERSIAN GULF

Sailors aboard the U.S.S. Theodore Roosevelt tossed a wreath into the Persian Gulf and fired a rifle salute to commemorate the attacks.

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ANN ARBOR, MICHIGAN

Students at the University of Michigan placed 2,977 small American flags in a grassy mall on campus, each representing a victim of the terror attacks. In Benton Harbor, Michigan, a 500-pound steel beam from the World Trade Center was put on display.

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COLUMBUS, OHIO

A field of nearly 3,000 flags was on display at the Ohio Statehouse, this one arranged in the shape of the World Trade Center towers, the Pentagon and a strip representing the Flight 93 crash site.

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MORRISON, COLORADO

More than 1,000 firefighters and other supporters, many in full bunker gear and carrying hoses, climbed the steps of the Red Rocks Amphitheatre outside Denver to honor firefighters killed on 9/11. Each participant carried a card with the name of a firefighter who died. The trek up and down the steps of the concert venue is the equivalent of climbing 110 stories.