In theory, the US and the rest of the world could know the name of the next President by 8 p.m. Washington time, (1 a.m. tomorrow morning, Irish time). But this is only if the exit polls for the Eastern states predict a clear winner when the polls close.
With the election so close, this may prove impossible. But if, for example, the exit polls predicted Governor George W. Bush winning Florida and Pennsylvania, with their total of 48 electoral college votes, he would be seen as having an unbeatable lead over Vice-President Gore. A win for Mr Bush in Michigan as well would probably have Mr Gore ready to concede victory to his Republican opponent.
This is because Mr Bush has the Rocky Mountain and most southern states safely in his camp according to all polls and Florida and Pennsylvania would put him over the top and give him the 270 electoral votes he needs to get to the White House.
But if the exit polls for the Eastern states are not conclusive and leave the two candidates still struggling to reach the magic 270 figure, then we have to wait another hour for results from the Central Time zone, where Wisconsin and Minnesota could tilt the scales to Mr Gore. But Mr Bush will be sure of Texas with its 32 votes.
The next time zone is the Rocky Mountain area which is already seen as a Bush sweep so it could all have to wait for the West coast time zone, three hours behind the East coast, where California, with its 54-vote prize, could be the decider in the presidential race.
But the smaller Pacific states of Washington and Oregon and their 18 votes could also swing it one way or the other.
So it could be breakfast time in the US or mid-afternoon in Ireland tomorrow before we know the winner for sure.