FORTY years later, America’s obsession with John F. Kennedy’s assassination – and its lasting effect on the course of history – continues unabated. All week long, TV specials have explored the question of who killed JFK and why and offered a litany of “what ifs” had the president lived to complete his term.

Surely no president ever attained such instant mythical status. But why?

As Michael Barone wrote in his book, “Our Country,” Kennedy’s death “did not fit the pattern” of such presidential icons as Abraham Lincoln and FDR. Unlike them, he wrote, “he had not led the nation in a war . . . his work was not finished; he did not look like a man worn old by the cares of office.”

On the contrary, he was young and seemingly vigorous as no president since Theodore Roosevelt 60 years earlier. And assassination itself, then unknown in 20th century America, suggested a kind of instant martyrdom; after all, only the most senior citizens could remember when a president of the United States had been gunned down.

All the more reason, then, why Americans from the beginning refused to accept the notion that a lone, disturbed gunman had murdered the president with no apparent motive. Gallup, in a poll taken less than a week after the assassination, found that only 29 percent of Americans believed Lee Harvey Oswald had acted alone.

“To accept that an act of random violence by an obscure malcontent could bring down a president of the United States is to acknowledge a chaotic, disorderly world that frightens most Americans,” writes Robert Dallek in his recent biography, “An Unfinished Life.”

Americans wanted JFK’s death to have meaning; as the years unfolded, and the nation was engulfed in traumas over Vietnam and civil rights, we all wanted to believe that the ordeal of the Sixties might have been avoided had JFK lived.

So many of us decided that sinister forces had to be at work – and they mythologized the slain president to a degree that his life and career became almost unrecognizable.

As a 10-year-old, I remember a Superman comic book that came out a few months after Dallas. In it, the Man of Steel chased a criminal into the future: The outlaw was captured only because he had fled to Nov. 22, 2063, and he was the only person who kept moving while everyone on Earth stood in silent tribute to “our greatest president.”

Today, not even all Americans could be expected to observe a moment of silence for JFK. The revelations of the past few decades have erased some of the luster of Kennedy’s presidency – unfairly tarnishing it, some would say; presenting a more honest and balanced appraisal, others would argue.

Yet many of the myths still remain. To conspiracy theorists like Oliver Stone, America’s Vietnam nightmare would never have occurred under John F. Kennedy; therefore, he must have been killed because he planned no wider war.

Indeed, JFK’s own friends and aides began insisting as much as opposition to the war grew. Theodore Sorenson, for one, claimed that JFK had vowed to withdraw all troops after he was re-elected in 1964 – a position that would hardly qualify Kennedy for a spot in his own “Profiles in Courage.”

Never mind that this flies in the face of everything JFK did in Vietnam, which drastically increased the U.S. role there. Despite his reluctance to become mired in a potential quagmire, and his skepticism over South Vietnam’s ability to enact genuine political reforms, he was convinced that abandoning Saigon would mean losing “the faith that the U.S. has the will and the capacity to deal with the Communist offensive.”

After all, despite those who would try to repaint him as a McGovern-type liberal, this was the president whose stirring inagural address had vowed that “we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of liberty.”

And it’s particularly telling that Robert Kennedy did not break with Lyndon Johnson’s Vietnam policy until 1967. Nor did he ever claim that LBJ had distorted his brother’s intentions. On the contrary: He came to oppose the war, he said, as someone who had helped make many of the mistakes that got America involved in the first place.

What happened in Dallas did not alter the course of history as much as many want to believe. What the events of that November did do, writes Michael Barone, was to shatter “national confidence in ways which were not fully apparent at the time and perhaps have never been fully appreciated.”

But now that only the middle-aged and elderly can recall the events of that long weekend, a more honest appraisal of JFK’s presidency, with both its successes and failures, and of the man himself, with both his vibrant charisma and his personal excesses, is taking shape.

Finally, it seems, Americans are heeding the words that Ted Kennedy delivered five years later about another slain Kennedy: “My brother need not be idealized or enlarged in death beyond what he was in life.”