Mr. Biden currently has 253 electoral votes. Should he win Pennsylvania, he would
surpass the necessary threshold of 270 Electoral College votes to capture the White House.
Since Thursday, the state has been at the center of efforts by Republicans to create
uncertainty about the results, by falsely claiming that election observers had not
been allowed to watch the tally.
While Philadelphia is an enormous source of Democratic votes, Mr. Biden’s strength in
Pennsylvania appeared to be more closely tied to improvements in the party’s 2016
performance in other parts of the state.
When votes began being counted, Mr. Trump appeared to have an early edge in
the state — at one point, the president appeared ahead by half a million votes.
But Mr. Biden steadily erased that lead as ballots, mostly mail-in and absentee votes,
were counted over the past two days.