The handwriting is on the wall if the election is razor thin between Biden and Trump. Both plan to contest the results. Unless there is a blowout for either candidate and an obvious win that no challenge can overcome, America's election night will continue on for perhaps a week or more. This is how:
If the polls are correct about voting habits, about 80% of Republicans plan to vote in person despite Covid-19, while 80% of Democrats plan to mail in their ballots. With such a disparity, the in person votes are counted nearly instantly in all the states. So, on election night, Trump, very well may seem like the winner in many of the battleground states. One can hear him and fellow followers declare victory on this night, while the Biden camp will not concede knowing that all of the mail-in ballots including absentee (that Trump himself uses) have not been counted. These ballots are counted by hand. It is a slow process as each envelope must be opened and certified etc. It is a very time consuming effort. With 80% of Americans voting in this manner, the mail in vote will be huge and will take several days after the election is over, maybe more.
As Trump declares victory, and as the mailed in votes are counted, Trump will spin his fake talking points of voter fraud to cement the win and casting suspicion on the results. Republicans will then rally around him citing cases of fraud as they did in 2016. Why?
As the mailed in votes are counted, the initial Trump win slowly may erode into a Biden win of the electoral votes of the state. Suddenly, Trump will slowly lose one key state after another until Biden is declared the winner several days or a week after the election night on Nov. 3rd. Furious, Trump will refuse to concede citing his conspiracy and voter fraud theories to cast doubt on the mail in vote count. Biden will have won the election with the electoral vote.
At this point, days or weeks after the election, America will still be in chaos thanks to Trump, a poor loser. He will then demand it be settled in the U.S. Supreme Court. The Court will determine who the winner is, which itself will be controversial for the loser. If Trump still is the loser, rioting may occur from the right wing nutcases and Trump may still refuse to concede and be forcibly removed from office.
Of course, if Biden loses, while he may concede more graciously, his party will not and protest the results in the streets, as well.
In any case, the 2020 election will go down in history unless there is a blowout of one candidate over the other.