960, there was good reason to suspect that John F. Kennedy only won the election thanks to fraud on the part of Lyndon Johnson in Texas and Mayor Richard Daley (father of Gore's campaign manager this year) in Chicago.
However Nixon, the loser, decided not to challenge the result. In his memoirs, Nixon claimed that he did not want to bring the presidency into disrepute in the tense Cold War climate of the time.
He probably also calculated that it would be bad for his own career to look like a bad loser. Gore has a similar calculation to make. Probably he has already decided to press the Florida challenge but, if it fails, to concede with as good grace as he can muster - probably, but no one can be certain.
Another factor that might influence him is that, if he were to recapture Florida, the Republicans might be tempted to reopen possible issues of irregularity in other states. That would put a number of cats among some potentially messy pigeons and would do serious damage to the already fragile reputation of the US electoral system.
The likely upshot, therefore, is that the result of the election will not be decided in a matter of hours, but will be known in a matter of weeks, and formally determined on 6 January, when the president of the Senate officially opens the Electoral College ballots.
Such a delay of almost two months would not be entirely cost-free. Political uncertainty could conceivably set off a more or less significant market fall. And the prestige of the presidency would suffer. How much does this near dead-heat matter? Does it reflect serious flaws in the constitutional system, or any unhealthy condition in the body politic?
Americans themselves are debating these questions, in online chat rooms, in bars, on television and in the columns of newspapers. Does it matter? Yes, it does. It has already been difficult for some years to move major legislation through Congress, essentially because party organisation counts for less and less.
Congressmen and senators get to Washington without much help from their party. They raise their own money and they buy their own TV spots. They are individualist and often stroppy. Only the conservative ideologues of the 1994 generation have shown much cohesion, and they fight likes cats in a sack.
What is more, they have been seriously discredited by the impeachment fiasco. Congress"s intractability is often put down to "divided government", the fact that Presidents often face majorities in Congress of the opposing party.
If either Bush or Gore had won convincingly, congressional leadership might have become easier. As it is, we should look for few bold initiatives - except perhaps on campaign finance and even electoral reform.
Specifically, there will be voices calling for abolition of the Electoral College. With that exception, it is most unlikely that many Americans will see the election as making a case for any major constitutional reform.
Indeed, it has been striking over the past couple of days how many politicians and officials, on television, in the very act of admitting irregularities in the working of the system, go out of their way to assert the superiority of American democracy.
An eighteenth-century Constitution may have shortcomings in the twenty-first century. But few Americans are willing to say so. Hardest of all to say is whether the election result reflects any broad distemper in the political system.
Many years ago Robert Kennedy pulled a stack of dog-eared three-by-five cards out of the bottom drawer of his desk to buttress his argument to me that America was so divided geographically and ethnically that it could not tolerate a party system that was also divided by class, like the politics of most European countries.
Yet something like that is exactly what has happened. Before the civil rights movement of the Sixties, American party allegiance essentially rested on the Civil War, and on the impact of mass immigration from Eastern and Southern Europe a hundred years ago. Southern reactionaries were joined in the Democratic Party with Northern workers and li