I’m surprised 1960 isn’t a more popular pick in this thread. Kennedy’s election led to his assassination, which spurned a domino effect of the escalation in Vietnam, Watergate, and the Reagan Revolution. I’ll go out on a limb and say no subsequent president after JFK would’ve ever been elected if it wasn’t for his assassination, and that the seeds of today’s political polarity were planted by his death.
This part is kind of true of every election. For example, if Dewey won in 1948, Eisenhower is most likely not elected President so there's a good chance Kennedy isn't either etc... I know for a fact Reagan wouldn't have been elected in 1980, which most likely means none of the Bushes, or Clinton, or Obama get elected either. The Country would also have gone on a much more moderate path (but still to the right of the path of 1933-1981 OTL) had Reagan not won and someone else had been elected in 1980.