Five decades after shots rang out from the Texas Book Depository, the United States will on Friday honor President John F. Kennedy, whose assassination is often said to mark the death of American innocence.
Kennedy was the fourth US president to be killed in office but the first whose death was caught on film and replayed repeatedly to a shocked nation.
An acclaimed orator and the first president of the television age, his death part-way through his first term at the age of 46 froze him in time as a great symbol of promise never realized.
The official account, based on four detailed investigations, records that he was felled by shots fired by troubled 26-year-old Marine Corps veteran turned Soviet defector Lee Harvey Oswald.
But to this day, many remain unwilling to accept that a lone gunman's seemingly deranged act could have had such a historic effect.
Many believe Oswald was either framed or working for a broader conspiracy, and their doubts have fed a sizable industry of conspiracy-themed books and films.
But, while Americans remain divided over the cause of Kennedy's death, they are remarkably united in seeing him as a great figure despite his limited time in office.
A Gallup poll to mark the anniversary found that three quarters of voters still rate him positively, placing him first among the presidents between the time of his immediate predecessor Dwight Eisenhower and that of his current successor Barack Obama.
And, although Kennedy died when the United States was in a nuclear stand-off with the Soviet Union, playing catch-up in the space race and mired in a war in Vietnam, many look back with nostalgia on the glamor and promise of his administration.
His wife, Jackie Kennedy, seen by millions on that November 22, 1963, distraught in a blood-spattered pink Chanel suit, has remained an iconic figure, and his surviving family members are leading characters in the American drama.
While many figures in his wealthy Boston Catholic clan have been touched by scandal, others achieved immortality of their own.
One of the slain president's brothers, his attorney general Robert Kennedy, was himself assassinated in 1968 and the other, Ted Kennedy, was a veteran figure in the Senate.
Kennedy's daughter Caroline will be absent from the anniversary ceremonies this week, but only because she has just set off for Tokyo as Washington's ambassador.
Events large and small, public and private, respectful and conspiratorial will mark his passing, focused on three cities, the Boston of his family power base, the Washington of his White House victory and Dallas, where his assassin struck.
On Wednesday, leading Democratic Party figures -- Obama and First Lady Michelle Obama and former president Bill Clinton and former first lady Hillary Clinton, Obama's heir apparent -- will honor him during a ceremony at Arlington National Cemetery just outside Washington.
There will of course be solemn speech but both presidents have already paid Kennedy the most telling tribute of all by co-opting his legacy in their own campaigns for office.
Clinton had the good fortune to be photographed meeting Kennedy in the White House Rose Garden in July 1963, and has reminisced about how he set his own eyes on the presidency after shaking JFK's hand.
Obama accepted Kennedy's torch of Democratic idealism in a key moment of the 2008 campaign, receiving the endorsement of Senator Ted Kennedy at American University in Washington.
In Dallas, where Kennedy nostalgia remains a mainstay of the tourist economy, bells will be rung at 12:30 pm, the moment of the shots, and a ceremony will be held at the scene in Dealey Plaza.
Americans who cannot make it to the ceremonies, or who are not among the tens of thousands who visit Kennedy's grave in Arlington each year, can at least enjoy an explosion of the already vast cultural output trading on his name.
Even though an estimated 40,000 books have already been published on the young leader, dozens more hit the shelves this year in the run-up to the anniversary, and at least two more television series are due to air.
Some deal with his behind the scenes life in his mythic household, the so-called "Camelot," including his many marital infidelities.
Others deal with the alleged conspiracy behind his death, and one full-blown historical counterfactual imagines the America of today had he lived.