Associated Press: Vision 2020: How soon will we know the US election outcome?
Wall Street Journal: When Will We Know the 2020 Presidential Election Results?
FiveThirtyEight: Will We Know The Winner On Election Night?
Lots of people will know who won by the time the polls close. Heck, even before the polls close.
And many of those people will be wrong.
And some of those who are wrong will never believe they're wrong.
More if it's close, fewer if it isn't, but some, no matter how big the gap between winner and losers, will know, to absolute certainty and beyond a shadow of doubt, that their preferred candidate actually won and was somehow cheated.
Quote, apocryphally attributed to Will Rogers, Mark Twain, and others, but probably a paraphrase of Josh Billings: "It's not what we don't know that hurts. It's what we know that ain't so."