Pennsylvania has emerged as one of the most important battleground states in the presidential election. As of Wednesday morning just after 9:15 a.m., with 64% of estimated votes counted, nearly 55% of voters had cast their ballots for President Donald Trump.

President Trump won the Keystone state by less than 1 percentage point in 2016, and outside of Florida, its 20 coveted Electoral College votes are more than any other traditional swing state. Florida has 29 electoral votes.

Both Trump and former Vice President Joe Biden used the final 48 hours of their presidential campaign to crisscross Pennsylvania, where nearly 9 million voters are spread from rural Carbon County to Philadelphia, the nation's sixth largest city.

Tuesday morning, Biden toured his boyhood home in Scranton, where he made one last appeal to white working class voters. Biden’s clearest electoral path to the White House runs through the state, but it’s not the only path.

“Looking back at 2016, Secretary [Hillary] Clinton poured her heart out into that election, and she won by nearly 3 million votes and that means nearly 3 million people more wanted her to be president of the United States but for the electoral college,” Biden’s National Press Secretary Jamal Brown told Yahoo Finance Live on Tuesday, before election results started coming in. “And so we took those lessons learned from 2016 to map out an expanded path to victory, and Pennsylvania is absolutely essential to that win.”

Thousands of Biden supporters showed up at Heinz Field in Pittsburgh Monday night for a socially distanced concert with John Legend and Lady Gaga. A dozen other events were scheduled in the state on Election Day.

Brown said the Biden campaign is not just focused on Pennsylvania; they are also looking at other key states where the race is expected to be close.

“We also are looking at key states like Florida... We’re looking at Texas where the early vote total was more than the 2016 total. We have Arizona, we have Texas, we have Pennsylvania, we have Wisconsin, we have Georgia,” Brown said. “We have a number of different pathways to hit that threshold of 270 [electoral college votes].”

But Election Day could turn into Election Week in Pennsylvania. It’s among the handful of states that didn’t begin counting absentee ballots until the morning of Election Day. And the state isn’t expected to have every vote counted until Friday, at the earliest. The polls closed in the state at 8 p.m. ET Tuesday.

This story was updated on Wednesday, November 4.

Alexis Christoforous is an anchor and reporter at Yahoo Finance. Follow her on Twitter @AlexisTVNews.

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