There has been much written since that momentous day about how the course of history was altered, along with innumerable conspiracy theories about whether or not Lee Harvey Oswald, the man who fired the shot that killed Kennedy, acted alone or in concert with others.
Every few years, another book or movie comes out purporting to have uncovered new evidence that sheds light on what for many remains a tantalizing mystery. But the overwhelming preponderance of evidence makes it all-but-certain that Oswald, a troubled drifter who had not, at the young age of 24, found his way, was in fact the lone gunman, acting out a deranged plot to obtain the recognition that had eluded him in life to that point. And what are we to make of the actions of Jack Ruby, the Dallas nightclub owner who shot Oswald two days later as he was being led out of a police station? Was Ruby part of a broader conspiracy to ensure Oswald's silence? Or was he just so upset about the President's death that he decided to take matters into his own hands?
Were signals missed? Probably. Should the Secret Service detail protecting the President been more vigilant? Hindsight is easy, but it's worth remembering that Kennedy himself overruled some of the recommendations of his security professionals, to ride in an open top convertible, on what was to be, after all, a political campaign trip. Texas was not Kennedy country, and with an election less than a year away, it was time to meet some voters.
Then tragedy struck.
How was America changed by JFK's assassination? It was a shock of the highest order to the national psyche, first of all. It had been more than 60 years since the last time a sitting American president - William McKinley in 1901 - was felled by a deranged gunman.
Endless debate has followed over whether or not Kennedy would have avoided the Vietnam trap that Lyndon Johnson, Kennedy's successor, fell or dived into, depending on your point-of-view. The answer of course is that we'll never know. Kennedy had stated, almost three months before his death during an interview with Walter Cronkite of CBS, that ultimately the problems in Vietnam would have to be settled by the Vietnamese themselves. But it's far from clear that Kennedy, who did not enjoy an over-abundance of political clout on Capitol Hill, would have been able to avoid the same mistake Johnson made, of over committing American military strength to an endless war with little strategic merit. Always sensitive to being viewed as "soft on communism," despite his gutsy performance in the Cuban Missile Crisis a year earlier, Kennedy might well have found it hard to resist calls for sending more troops to what became, in short order, a seemingly endless quagmire.
On civil rights, the other defining issue of the wild and tumultuous decade that was the 1960s, most of the legislation designed to protect the status of African-Americans was passed in 1964-65, partly out of sympathy for the dead President and also because of the remarkable political skills of Lyndon Johnson. Had Johnson remained sidelined as the vice president almost no one ever heard about on the evening news, the Civil Rights Act and the Voting Rights Act might well have languished for many more years to come.
Beyond all of that, however, is the more emotional clutch of seeing a young, vibrant, charismatic public figure cut down in his prime, with so much unfinished business ahead of him. Kennedy was in a sense, the first modern president of the media age. A photogenic man, with an attractive and equally charismatic wife, and a young family, all the trappings of the cultural "Camelot" they brought to Washington D.C. - his sudden and shocking death erased something of a sense of innocence that attaches still to the postwar era of the 1950s and early 60s. That era was far from innocent, and shrouded by the threat of thermonuclear war and fierce ideological rivalry between the West and the Soviet Union. Still, in a way, the 1960s can be said to have begun with Kennedy's assassination, with the arrival of the Beatles on the Ed Sullivan Show a few months later marking another, if more cultural, turning point. Somehow the nation was not the same one it had been on the morning of Nov. 22, 1963, again. We started down a road that was more jaded, less trusting in the institutional word; more cynical and less certain everything was going to always work out OK in the end because we were by definition the guys in the white hats. It was only a few short years afterwards before massive antiwar demonstrations and Marches on Washington became commonplace. Somehow, those scenes are hard to picture in an Eisenhower-era America. But parts of that era was also something of a dreamworld disconnected from reality, and had to come to an end.
For a majority of the population, Kennedy's assassination is an historical event read about in textbooks, or more likely today, online. For those who do remember it, it's a kicker to think that it's been 50 years - 50 years - since that awful day. Where has all the time gone? Where have all the flowers gone?