The COVID-19 pandemic has disrupted countless aspects of everyday life for months now, and the 2020 election is no exception. States across the country, including Massachusetts, have responded by greatly expanding early voting and mail-in voting options for voters.

For their part, voters have responded, with more than 92 million Americans having already cast their ballot, according to the U.S. Election Project. Here in Massachusetts, between mail-in and early voting, nearly half of registered voters have already voted.

But this unprecedented interest in voting before Election Day has also injected unprecedented uncertainty into what Election Day will look like.

Many of these states have never dealt with mail-in voting anywhere near the scale they are seeing in 2020. And in many cases, expanding early and mail-in voting options meant states had to pass new elections laws.

Everyone from pundits to elections experts to elected officials have said that the upshot is that it could be days, or even weeks, until we know who won the election.

Why it could take a few days

At the end of the day, voting is a process — and it takes time for votes to be cast, counted, and reported, even in normal times.

“As anyone who’s ever voted knows, if you go to vote, most of the poll workers are senior citizens.” said John Lappie, professor of political science at Plymouth State University in New Hampshire. But Lappie said concerns about COVID among this high-risk group has meant many experienced poll workers have chosen to sit this cycle out. “So a lot of polling places are going to be understaffed,” he said, noting his own town of Plymouth, N.H., has appealed to local college students to become first-time poll workers this year in order to fill vacant positions.

Lappie said the lack of staff and experience at polling locations throughout the country means that routine activities may take longer at a lot of polling places.

But the true timeline wildcard is the dramatic increase in the number of mail-in ballots that states across the country will be handling this year.

Counting mail-in ballots involves several steps, many of them that have to be done by hand, such as opening envelopes, verifying signatures, sorting ballots by precinct, and feeding validated ballots into voting machines to be counted.

“All of those things take a lot more time to do than counting Election Day returns, especially when you’re understaffed,” said Lappie.

Many states will be handling mail-in ballots at numbers never before seen this year, adding to uncertainty about the timeline. And elections, even for president, are run at the state level — meaning each state does things a little differently.

In some states, like Arizona, Florida and North Carolina, elections officials have been processing mail-in ballots for weeks — opening envelopes, verifying signatures, sorting ballots — meaning they could be able to report results as early as Election Day.

But in other states, including Wisconsin and Pennsylvania, mail-in ballots cannot begin to be processed until Election Day.

“In those states, it could be seriously delayed,” said Lappie.

Wisconsin Gov. Tony Evers told CNN on Sunday, “People need to relax, and it may take a day or so longer than it usually does.”

Pennsylvania Secretary of the Commonwealth Kathy Boockvar has said that she expects “the overwhelming majority” of votes will be counted by Friday, Nov. 6.

Furthermore, the way in which state will reports results also varies. In Massachusetts, for example, results are released as they are determined following the close of the polls. And those results will include a mix of early, mail-in, and in-person votes. In neighboring Rhode Island, however, in-person votes will be released first. A first count of mail-in votes will not be released until 11 p.m. on election night.

This matters because of the expectation that supporters of each presidential candidate also have a preference when it comes to how they vote this year.

“The Election Day vote will be heavily Republican, the vote-by-mail will be heavily Democrat,” said Lappie.

As such, Lappie says it’s important to pay attention to the specifics as to which votes are being reported as election night wears on.

“In Wisconsin, Michigan and Pennsylvania, if — as would normally be the case — the Election Day results are tabulated first and then released to the public … you could have early election results that look very good for the president that ‘turn into a victory’ for Joe Biden as the mail-in ballots get counted,” he said.

In states like North Carolina and Florida, he said the opposite could be true.

“The early returns there could be very favorable for Biden and then narrow as the Election Day results get released,” he said.

Why it could take a few weeks

In a word: Litigation.

An analysis by USA Today found that 230 election-related federal lawsuits were filed from Jan. 1 to Oct. 23, higher than any of the past three presidential election years during the same time period.

Some of these cases have been resolved. Some have not. Others could be appealed. And new challenges are expected to be brought in the courts following Nov. 3.

Many of these lawsuits concern small details, like the specifics of deadlines or under what specific conditions a mail-in ballot should be rejected. But in a close election, especially in crucial swing states, decisions about these small details could make a big difference.

Take Pennsylvania, a state seen as critical to both candidates, as an example.

One of the tools elections officials use to verify a voter’s identity with mail-in ballots is signature verification. A number of states, including Massachusetts, match each voter’s signature on their mail-in ballot envelope against some other copy of their signature on record to ensure it is indeed the same person.

In Pennsylvania, the Secretary of State said that signatures on a ballot are required, but don’t need to be matched against another signature in order to be valid. In late October, the Pennsylvania State Supreme Court agreed, ruling that “county boards of elections are prohibited from rejecting absentee or mail-in ballots based on signature comparison conducted by county election officials or employees, or as the result of third-party challenges based on signature analysis and comparisons.”

For now, that means ballots in Pennsylvania will not be rejected if there is a signature discrepancy. But that ruling could be appealed to the U.S. Supreme Court following the election.

Also in question in Pennsylvania is the status of ballots that are postmarked by Election Day and arrive after the polls close on election night but before 5 p.m. on Nov. 6. The Pennsylvania State Supreme Court has ruled those ballots should be counted, as state election laws allows. A 4-4 deadlock on the issue in the U.S. Supreme Court in October kept that ruling in place.

So, as of now, they will count. But the state will separate those ballots as their validity could yet be overturned by the U.S. Supreme Court after the election, now that Justice Amy Coney Barrett has been sworn in and could theoretically break a tie.

And that’s just one state.

In Minnesota, they will also separate ballots postmarked by Election Day and received until Nov. 10. Whether those votes will ultimately count is still in question. In Nevada, Republicans are asking that mail-in votes in Clark County stop being counted until observers are given an opportunity to see exactly how ballot-envelope signatures are being verified.

If any of these groups of ballots in one or more of these states could determine the winner, you can expect to see battles in the courts over whether they should count.

That could drag the results out for weeks.

How many weeks? Circle Dec. 14 on your calendar. That is the date by which, according to federal election law, the Electoral College — the group of electors who technically elect the president and vice president — must cast their votes.

“There is a hard deadline,” said Lappie. “All of these things need to be resolved between Nov. 3 and Dec. 14.”

Why we could know on Election Night

Florida and North Carolina, two key swing states, are among those where mail-in ballots have been getting processed for weeks already. That should put both states in a strong position to report reliable results on election night that include both mail-in and in-person, Election Day votes.

Depending on how close the vote is, either or both of these states could be “called” for one candidate or the other on election night, just like might happen in a more typical election year.

Lackie said that a clear Biden victory in either of those two states would essentially secure a Biden win, “because President Trump does not have a plausible path to a majority that doesn’t include both North Carolina and Florida.”

Lackie says a Trump victory in these two states would be promising for the president, but would not be as definitive a result, as Biden has a viable path to victory that does not include him winning either Florida or North Carolina.

Polls show a close race in both states.