In 2016, the world knew that Donald J. Trump had won the presidency by the time it woke up the morning after Election Day. In 2020, the race wasn’t called for Joseph R. Biden Jr. until the following Saturday.
This year, either timeline is conceivable, depending on how close the race is. If the result comes down to a few thousand votes in a handful of states, we could be in for a 2020-style wait. But if one candidate outperforms the current polls, which are showing the closest race in many years, the outcome could be clear much sooner.
What happened in 2020?
The 2020 election was held on Tuesday, Nov. 3, but seven decisive states — Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin — remained uncalled the next morning.
The Associated Press called Michigan and Wisconsin for Mr. Biden on Wednesday, bringing him to the brink of an Electoral College majority but not over the threshold. Then — because of the time required to count mail ballots, which had been cast in greater numbers than ever before thanks to the pandemic — the nation watched results trickle in slowly for three days before any more states were called.
It was not until Saturday, Nov. 7, that news organizations confirmed Mr. Biden as the winner of Pennsylvania and, with it, the presidency. (Nevada, Georgia, Arizona and North Carolina were called even later, but the overall verdict arrived shortly before noon on Saturday.)
On election night itself, understanding how states are leaning can be complicated by red and blue “mirages” — artifacts of some states counting mail ballots before in-person ballots, and some states that do the reverse. Because Democrats were disproportionately likely to vote by mail and Republicans disproportionately likely to vote in person, one candidate sometimes appeared to be far ahead, only for the other candidate to surge later.
