While many winners on election night may quickly be apparent, the rise in mail voting due to the pandemic is expected to hold back the release of full results in many key states.
Many states will not have complete results on election night:
A large number of voters could still be pending even after the early and in-person ballots are counted. At least 98 percent of unofficial results announced by noon the day after the election is anticipated by just nine states. After Election Day, 22 states and the District of Columbia allow postmarked ballots to arrive, so the timing will depend on when they are returned by voters.
On election night, New York and Alaska will not announce any postal votes. Officials in Michigan and Pennsylvania, two main battleground states, have said that full official counts could take several days. (Rhode Island had also intended not to release mail votes that night, but its election board voted Monday to begin publishing them at 11 p.m.)
More provisional votes cast could also result from an increase in mail voting, raising the number of ballots counted later. In many states, voters who are eligible to vote in the polls may cast an interim ballot, which is set aside and counted only if eligibility is confirmed later.
The number of provisional votes is generally not sufficiently high to be major, although there is evidence from early voting that this election might be different. Some electors are allowed to vote provisionally in at least 23 states if they initially request a mail ballot, but later opt to vote in person (other states have different methods of preventing double voting). Provisional voting at the polls will slow down lines, and those ballots are typically the last ones to be checked and counted.
It is pertinent to mention here that until final certification, which happens in each state in the weeks following the election, results are never official.