Four years after “Election Week” in 2020, voters are heading to the polls wondering: How long will it take for states to count their ballots this year?

Several dynamics have changed since the last presidential campaign: Many voters have returned to in-person voting in the wake of the Covid pandemic, and many states have rewrote their laws to allow election officials to begin processing mail-in ballots before Election Day. These two changes are expected to speed up tabulation, but it could still be days before a full picture of the election results is available.

In close elections, it takes longer for news organizations like NBC News to call because winners may be determined through absentee and provisional ballots, which can take days for election officials to process and count.

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Mail-in ballots take more time to process than votes cast in person because poll workers must verify voters' identities and remove them from envelopes.

And provisional ballots are cast by people who poll workers could not immediately confirm were eligible to vote when they cast their ballot. These ballots will be separated from the approved ballots until officials can verify that the votes are valid.

As Election Day approaches, here's a rundown of the rules for how the seven key battleground states likely to win the presidential election can count those ballots.

Arizona

Postal ballot: Arizona voters overwhelmingly vote by mail, so last-minute ballots can result in longer counting times. State officials say counting ballots could take 10 days. However, according to the Arizona Secretary of State, the counting of absentee ballots can begin upon receipt.

Provisional ballots: Provisional ballots that require additional research by officials or documents from voters can be counted up to 10 days after the election under state law.

Georgia

Postal ballot: Georgia will begin processing mail-in ballots on October 21 and can be cast until polls close on Election Day.

Provisional ballots: Voters have three days to show ID or have registrars confirm their identities after casting provisional ballots, but results are expected quickly.

Michigan:

Postal ballot: Major jurisdictions in Michigan can begin processing mail-in ballots on October 28, giving election officials a much-needed early start on reviewing mail-in ballots. Mail-in ballots must be received by the polls close on Election Day.

Temporary devices: Clerks have until November 12th to process the provisional ballots.

Nevada

Postal ballot: Mail-in ballots must be postmarked by Election Day and received by November 9th. Election officials can begin processing as soon as they receive them.

Provisional ballots: Voters have three days after election day to provide proof of residency and identity if necessary. If their signatures don't match those on the mail-in ballots, they have until November 12 to “cure” their ballots.

North Carolina

Postal ballot: Mail-in ballots must be received by Election Day and are sometimes processed throughout October.

Provisional ballots: Voters who were unable to provide sufficient identification at the polls have until Nov. 14 to provide the required identification to election officials. Election officials can process additional provisional ballots until counties begin seeing results on Nov. 15.

Pennsylvania

Postal ballot: Election officials must receive mail-in ballots by the time polls close on Election Day. Processing begins at 7 a.m. on Election Day, making the state one of the last battlegrounds to begin verifying signatures and personal information on ballots.

Provisional ballots: County boards must review and decide within a week of the election whether provisional ballots will be counted.

Wisconsin

Postal ballot: Postal ballots must be received no later than Election Day. Processing begins at 7 a.m. local time on Election Day, making Wisconsin the last state to begin processing ballots.

Provisional ballots: Voters have until 4:00 p.m. on the Friday following the election to provide election officials with all necessary documentation, such as: B. Proof of identity to ensure that their ballots count.