The coronavirus pandemic has changed everything about 2020 - including what to expect from the final act of the election. 

A massive increase in early and mail voting, with many voters seeking to avoid crowded polling places, has reshaped how and when most ballots are counted, creating uncertainty around when results will be known. Some states have already surpassed their 2016 vote totals, and election experts predict that the rate of mail voting will range from 50 to 70 percent nationwide this fall, compared with roughly 23 percent in 2016. For the first time in history, most Americans are expected to cast their ballots before Election Day.

As a result, while many Americans are accustomed to voting on Election Day and learning results that night, Election Day 2020 in fact marks the end of a lengthy voting period and the start of a potentially lengthy counting period. Some states plan to report results the night of Nov. 3, but others expect it to take longer, depending on when they begin processing and counting mail-in ballots. Even in a typical election year, ballot counting always goes past election night. Results are not official until states certify them, sometimes weeks after the election takes place.

The Washington Post wants readers to be prepared to interpret what is happening in these unusual circumstances. Here are some frequently asked questions about what we will know and when.

- When will we know who won the presidential race?

It's hard to say, both for the presidential and for down-ballot races. We do know that some states won't have complete results for weeks.

Nearly half of all states will accept ballots that arrive by mail during a certain window after Election Day if their postmark indicates they were sent by Nov. 3 or an earlier deadline. And roughly 30 states allow voters to fix errors that would otherwise lead to their ballots being rejected; in states where this is permitted after Election Day, it could draw out the time before final results are announced.

Meanwhile, early results in some key states may provide enough information to declare a winner. States that are allowed to process and count ballots before Election Day and have strong early in-person and mail voting could release a sizable proportion of the results after polls close.

Most news organizations plan to use extra caution this year when projecting winners because early results may not provide the full picture. In some states, ballots cast in person on Election Day will be reported first, and they could favor President Donald Trump, since polls show a majority of his supporters plan to cast ballots on Election Day. In other states, mail votes cast before Nov. 3 will be reported first or included in preliminary tallies. Those could include a disproportionate number of Joe Biden votes, since more Democrats have embraced mail voting this year.

Candidate declarations of victory don't factor in.

- How do swing states report results?

We will probably get earlier results in states with two key traits: voters who have widely embraced early in-person or mail voting, and rules that let officials process and count mail ballots before Election Day. Arizona, Florida and North Carolina could provide information quickly, experts say, while states including Pennsylvania and Michigan could lag behind.

Arizona: The state allows mail ballots to be processed and counted before Election Day, which means voters can expect to see more advanced results on election night, if everything goes according to plan. The process can start earlier than it did in 2018, when results remained unclear in a major Senate race for nearly a week. At least one major county has also upgraded its equipment.

Election officials plan to release initial results around 8 p.m. local time, or about an hour after polls close, combining all ballots cast before Election Day by mail and in person. The next ballots to be counted will be those cast at polling locations on Election Day, followed by mail ballots returned that day.

Florida: The state allows mail ballots to be processed and counted before Election Day, which means voters can expect to see more advanced results on election night, if everything goes according to plan.

Initial statewide results are expected in Florida at 8 p.m. Eastern time on election night and will include ballots cast early in-person and by mail.

Georgia: Mail ballots can be processed before Election Day, but cannot be counted until polls close.

Secretary of State Brad Raffensperger has predicted that results for "very, very close" races will be available one or two days after the election at the latest. Results for less competitive races will be available on election night, he said.

Michigan: In jurisdictions with more than 25,000 people, mail ballots can be processed starting Nov. 2. Other jurisdictions must wait until Election Day, when ballots are counted.

Michigan expects to have unofficial statewide results available Nov. 6, if not earlier, once all ballots are counted. Counties may release preliminary results before that.

Minnesota: The state allows mail ballots to be processed and counted before Election Day. Officials expect to release preliminary results after polls close around 8 p.m. local time that combine Election Day in-person, early in-person and mail votes.

North Carolina: Mail ballots can be processed before Nov. 3, but not counted until that day. Still, a heavy volume of early in-person votes this year means voters can expect to see more advanced results on election night, if everything goes according to plan.

North Carolina expects to report results from early in-person votes and mail ballots cast before Election Day after all polls close statewide at 7:30 p.m. Eastern. Election Day votes will be counted last. The state expects it will report results on election night reflecting more than 95 percent of votes cast in the election.

Ohio: Mail ballots can be processed before Election Day, but not counted until polls close. Ohio plans to release preliminary results on election night that combine Election Day in-person, early in-person and mail votes returned by close of polls.

Pennsylvania: Mail ballots cannot be processed or counted until Election Day, despite local election officials pleading with the legislature to give them more time.

Secretary of State Kathy Boockvar has predicted that the vast majority of ballots will be counted "in a matter of days" or "by the weekend (after the election) ... maybe even significantly sooner." A spokeswoman said the state is making changes to its system to provide an analysis of different types of votes cast and report the number yet to be counted, broken down by county.

Wisconsin: Mail ballots cannot be processed or counted until Election Day.

Wisconsin has no statewide reporting process for unofficial results on election night, but municipal clerks are required to report their tallies to county clerks within two hours of finishing the count. Most mail ballots are counted at precincts where the voter would have cast a ballot in person.

Election officials have predicted they will finish counting on election night or the day after.

- Why does an increase in mail ballots make a difference?

Mail ballots must go through several steps before they are counted, including a review by election officials to ensure their validity. That process takes more time than counting ballots cast in person at a polling location - and in some states, officials are not allowed to begin until Election Day.

While it may be slower, there's no evidence that mail voting leads to widespread fraud, and delayed reporting of mail ballots is not a sign of a problem with the vote.

- When will the results become final?

Americans typically know who won elections long before the results become official.

Each state has a different timetable for canvassing a general election, which involves compiling returns, making sure every ballot is accounted for and certifying the results. The process usually takes place later in November and sometimes extends into December.

This year, close margins will increase the likelihood of legal fights over which ballots should count. But a handful of deadlines will also place pressure on courts to resolve disputes quickly.

States are supposed to appoint presidential electors by Dec. 8 - or at the latest, Dec. 14, when the electors meet in state capitals to cast their votes. Certificates of election from the states are counted by members of Congress on Jan. 6.

- How did the pandemic affect voting during the primaries?

The rapid shift toward mail voting during the primaries meant that many results were delayed. Twenty-three states held primaries after mid-March, and they took an average of four days to report nearly complete results, according to a Post analysis. In Pennsylvania and Wisconsin, results took roughly six days to be released, while in Georgia, they took 10 days.

The most dramatic example was New York, where it took roughly six weeks to resolve two congressional Democratic primaries.

- Could we see a repeat of what happened during the 2000 presidential election? Remind me what happened then.

People concerned about whether results will be clear this year point to the election meltdown of 2000, when an extremely tight vote margin in Florida between then-Texas Gov. George W. Bush, the Republican, and then-Vice President Al Gore, the Democrat, led to a mandatory recount.

As the process became mired in litigation, the Florida Supreme Court ordered a hand recount of roughly 45,000 ballots that were recorded as not registering a clear choice in the presidential race (many because of what became known as "hanging chads"). But the Bush campaign succeeded in petitioning the U.S. Supreme Court to block the order, and the court ultimately reversed it. The result was a Bush victory in Florida, which handed the then-governor a majority of electoral votes, while Gore won the popular vote.

Experts have said it is unlikely that a similar situation, in which a Supreme Court decision directly shapes the race's outcome, will unfold during this year's presidential election. That's because a number of rare circumstances would have to collide for it to happen, including a race that hangs on the outcome in a single state, a tiny margin of victory in that state, a considerable number of ballots where voters' choices are unclear and a dysfunctional recount process.

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The Washington Post's Ashlyn Still and Kevin Schaul contributed to this report.