• There were 2.41 million mail-in ballots received in Pennsylvania by Monday
  • Pennsylvania counts votes at 7 a.m. on Election Day 
  • Adding to a possible delay is that at least seven counties which lean Republican — Beaver, Cumberland, Franklin, Greene, Mercer, Monroe and Montour — will wait to count the mail-in ballots the day after Election Day.

One of the more curious stories of Election Day may not only be, "Who won Pennsylvania?" but also, "When will we know who won Pennsylvania?"

In 2016, the Associated Press called Donald Trump the winner of Pennsylvania at 1:35 a.m ET. But in 2020, there is expected to be a stronger voter turnout and it could take much longer to tabulate all the votes.

Trump famously upset Hillary Clinton in Pennsylvania, a key battleground state, by just 42,292 votes among 6.16 million votes. Democrats in 2020 are hoping to flip the state back after five consecutive wins in presidential elections and with nominee Joe Biden hailing from blue-collar Scranton.

Adding to the drama of Pennsylvania's outcome is the possibility that the winner may not be determined for days and that Trump may have a big early lead well before all the votes are counted.

One of the issues with quickly determining the winner is the record number of mail-in votes.

There were 2.41 million mail-in ballots received in Pennsylvania by Monday, with roughly 66% from Democrats, 23% from Republicans and 11% from third-party or unaffiliated registrants. Experts have noted that Democrats in the state prefer to vote by mail, while more Republicans vote in person on Election Day.

The 2.41 million mail-in ballots account for roughly 78% of Pennsylvania voters who requested a mail-in or absentee ballots.

Pennsylvania counts votes at 7 a.m. on Election Day and the counting for rural areas is expected to be quicker than metropolitan counties that will report later.

Meanwhile, ballots that are postmarked on Election Day can be counted up until Friday. Adding to a possible delay is that at least seven counties which lean Republican — Beaver, Cumberland, Franklin, Greene, Mercer, Monroe and Montour — will wait to count the mail-in ballots the day after Election Day. Trump has stated that the election should "end" on Election Day, which might be to his advantage since many rural counties will have a faster time counting ballots.

“The outcome of Tuesday’s election could well depend on Pennsylvania. It is vitally important that the more than 3 million ballots cast by mail here be counted as soon as possible,” Pennsylvania's Secretary of State Kathy Boockvar said in a statement. “The country will be looking to Pennsylvania for accurate and timely results.”

Just 1.5 million Pennsylvanians voted by mail in the June primary and it took some counties weeks to count all the ballots. The deadline is Nov. 10 for military and overseas ballots.

Polls, meanwhile, open at 7 a.m. local time on Tuesday and remain open until 8 p.m.

“Elections are never … finished on Election night and certainly, we’ve never had 2.5 to 3 million mailed ballots to count before. So you know, I urge as always voters, press, you know, everybody to ignore completely unsubstantiated claims that have no basis in reality and that’s what it would be," Boockvar told The Patriot-News in Harrisburg.

Adding to the confusion is the possibility that legal challenges may await after the election.