Ground Zero, more familiar these past 10 years for bagpipes playing Amazing Grace and solemn speeches and arguments over what to build to honour the September 11 dead, became, for the first time, a place of revelry.
Lisa Ramaci, a New Yorker whose husband was a freelance journalist killed in the Iraq war, said: "We've been waiting a long time for this day.
"I think it's a relief for New York tonight just in the sense that we had this 10 years of frustration just building and building, wanting this guy dead, and now he is, and you can see how happy people are."
She was holding a flag and wearing a T-shirt depicting the twin towers and, in crosshairs, bin Laden.
Nearby, a man held up a cardboard sign that said: "Obama 1, Osama 0."
In Times Square, dozens stood together on a clear spring night and broke into applause when a New York Fire Department vehicle drove by, flashed its lights and sounded its siren.
A man held an American flag, and others sang The Star-Spangled Banner.
In Washington, in front of the White House, a crowd began gathering before President Barack Obama addressed the nation late last night to declare: "Justice has been done."
The crowd grew, and within half an hour had filled the street in front of the White House and begun spilling into nearby Lafayette Park.
Marlene English, who lives in Arlington, Virginia, and lobbies on defence issues, said: "It's not over, but it's one battle that's been won, and it's a big one."
She said she has baked thousands of biscuits to send to friends serving in Iraq and Afghanistan over the years and she was at the White House because they could not be.
The celebrations came together late last night after Americans began hearing about the death of bin Laden from bulletins on television, texts and calls from family and friends, and posts on social networking sites.
Bin Laden was killed in his luxury hideout in Pakistan, early today local time and late Sunday night in the United States, in a firefight with American forces. Mr Obama said no Americans had been harmed in the operation.
When news of the president's announcement began to filter across the country, the New York Mets and Philadelphia Phillies were in the middle of a game in Philadelphia, and chants of "USA! USA!" began among the crowd at Citizens Bank Park.
Fans could be seen all over the stadium checking their phones and sharing the news.
The chant - "USA! USA!" echoed in Dearborn, Michigan, a heavily Middle Eastern suburb of Detroit, where a small crowd gathered outside City Hall and waved American flags.
Across town, some honked their car horns as they drove along the main street where most of the Arab-American restaurants and shops are located.
At the Arabica Cafe, big-screen TVs that normally show sports were all turned to news about bin Laden. The manager there, Mohamed Kobeissi, said it was finally justice for the victims.
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