Polls for the general election may close Tuesday night, but the country will potentially have to wait for weeks to receive the final results. Many battleground states only have partial counts of their votes as of early Wednesday morning, and will need time to finish their counts.

County boards of elections in Pennsylvania must receive mail-in ballots from voters by Friday at 5 p.m., and they must be postmarked on or before Tuesday in order to be counted. This buffer time between the end of the election and the deadline for mail-in ballots means there is still time for election offices to receive and count more votes even after Tuesday as the ballots trickle through the postal system. Overseas ballots are not due until the following week. According to The Atlantic, the approximately 648,000 overseas Americans who requested ballots may not necessarily change the tide of the election, but their votes could affect the results of especially close races.

According to the U.S. Elections Project, about 92.1 million voters across the country requested mail-in ballots for this election, and election offices have received about 65.2 million of them. The number of mail-in ballots this year is about one and a half times the roughly 47 million mail-in and absentee votes cast in 2016.

Allegheny County said 125,383 of 348,485 ballots received have been scanned as of approximately 10:30 p.m. This is about 36% of the ballots.

At a press conference held Monday, Pennsylvania Secretary of State Kathy Boockvar said there is no basis on which anyone can claim the election is over until every single vote is counted.

“There’s no basis in Pennsylvania or in federal law for a candidate to declare a race is done,” Boockvar said, “until the statutory requirements for that election are done.”

According to Boockvar, counties begin pre-canvassing mail-in ballots on Election Day at 7 a.m. in order to keep vote counting as efficient as possible. The process of pre-canvassing involves the opening and tallying of mail-in and absentee ballots without recording or publishing the results. The first set of results is released shortly after polls close at 8 p.m.

Boockvar said due to the sheer quantity of ballots and the fact that they require both mechanical and human processing, it will take time to finalize election results. Boockvar said registered voters in Pennsylvania have requested 3 million mail-in and absentee ballots, 2.5 million of which have already been received.

“It takes time for votes to be counted,” Boockvar said. “Elections are never finished on election night, and certainly we’ve never had 2.5 [million] to 3 million mail-in ballots to count before.”

She said counties will work 24/7 to count all the ballots and will update results online as they come through. Boockvar added that certain counties in Pennsylvania don’t plan to begin counting mail-in ballots until the day after the election, which could delay results for some races.