At dawn, Attorney General Eric Holder made a gravesite visit to honor Kennedy, bowing his head and placing a Justice Department commemorative coin at the stone.
DALLAS — U.S. President John F. Kennedy was remembered as a transcendent leader of a rising nation at a ceremony in Dallas on Friday, the 50th anniversary of his assassination.
"Our collective hearts were broken," Dallas Mayor Mike Rawlings told a crowd of about 5,000 who came to a frigid Dealey Plaza, near where Kennedy was slain, for a commemoration marked with prayer, song and tears.
Remembered fondly for his youthful vigour and his glamorous wife, Kennedy remains one of Americans' favourite presidents for his handling of the Cuban missile crisis, his call to public service with programs such as the Peace Corps and a promise - later fulfilled - to land an American on the moon before the end of the 1960s.
The assassination cut short "Camelot," as the 1,000 days of the Kennedy presidency became known. He was 46 when he died.
"If that hadn't happened, history might have changed somewhat. He was a different kind of president," said Douglas Ducharme, a Canadian who came to attend the event.
The memorial was the first for Dallas, which had avoided any commemoration of the darkest day in its history. In previous years, conspiracy theorists gathered in Dealey Plaza to express their doubts of the official conclusion that gunman Lee Harvey Oswald acted alone.
Two days after the assassination, Dallas nightclub owner Jack Ruby shot Oswald dead while he was police custody. Ruby died in jail three years later.
A WREATH AT THE GRAVE
At Arlington National Cemetery in Virginia where Kennedy is buried, family members laid a wreath at his grave, where Jackie Kennedy and two of their children also are buried.
At dawn, Attorney General Eric Holder made a gravesite visit to honour Kennedy, bowing his head and placing a Justice Department commemorative coin at the stone. Holder then walked a short path to the grave of Robert F. Kennedy, who had served as attorney general under his brother. The current attorney general bowed his head and left another coin.
At the John F. Kennedy Library and Museum in Boston, a steady stream of people came in to view artifacts, including a video of Kennedy's state funeral and a display of the saddle, sword and boots of Jack Black, the riderless horse who had led the procession.
Hundreds of people also lined up to write their thoughts and sign their names in four large guest books set up at the museum on pedestals decorated with flowers.
"Some people view Kennedy's assassination as the moment the nation lost its innocence," said Alex Loughran Lamothe, a 23-year-old volunteer for City Year - an organization modelled on Kennedy's Peace Corps program - who was helping at the exhibit.
New York City tabloids on Friday included inserts of their reprinted 1963 editions reporting on the Kennedy assassination.
The New York Post, which at the time was an afternoon newspaper, ran an extra edition on November 22, 1963, that cost 10 cents and was headlined "JFK SHOT TO DEATH" with a stock portrait photograph of Kennedy.
Dallas was seen as a pariah city for years after the assassination. That stigma started to fade decades ago, and now, The Sixth Floor Museum in the former Texas School Book Depository - where police found Oswald's rifle - is one of the city's biggest tourist attractions.
"Dallas came under a great deal of international criticism after the assassination. It was called the 'City of Hate,'" said Stephen Fagin, associate curator The Sixth Floor Museum.
Amid the Cold War paranoia and simmering racial tension of the 1960s, a small but influential group of arch-conservatives protested Kennedy's visit to Texas, saying he was soft on communism and should stay away.
In recent days, the city removed a large "X" embedded into the pavement by an unknown person or people that marked the spot on Elm Street where Kennedy was shot in the head.
The "X" had been seen as tasteless by many while the official observance - a small plaque on the plaza's noted "grassy knoll" - had been criticized as inadequate.
The conspiracy theorists also came to Dallas for the 50th anniversary but were left out of the official event, with one group gathering at a nearby sandwich shop.
Recent surveys show that Kennedy remains one of the most admired U.S. presidents and that the majority of Americans believe that Oswald had co-conspirators in the murder.
Thousands of books, news articles, TV shows, movies and documentaries have been produced about that fateful day in Dallas, and surveys show a majority of Americans still believe in the conspiracy theories, distrusting official evidence that points to Oswald as the sole killer.
Despite serious questions about the official inquest, and theories purporting that organized crime, Cuba or a cabal of U.S. security agents was involved, conspiracy theorists have yet to produce conclusive proof that Oswald acted in consort with anyone.
Hugh Aynesworth, a reporter in Dealey Plaza 50 years ago who witnessed the assassination and also saw Oswald shot dead by Ruby, has spent a lifetime investigating the killings and debunking suspected plots.
"We can't accept very comfortably that two nobodies, two nothings - Lee Harvey Oswald and Jack Ruby - were able to change the course of world history," he told Reuters.
Additional reporting by Barbara Goldberg in New York, David Ingram in Arlington, Brian Snyder and Richard Valdmanis in Boston, Pavithra Sarah George in Dallas.
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