HARRISBURG, Pa. (AP) — Democrat Joe Biden has won Pennsylvania, surpassing the 270 electoral vote threshold to take the White House and become the 46th president of the United States.

Biden also carried Arizona, Wisconsin and Michigan on his path to the presidency, flipping states that President Donald Trump won in 2016. Pennsylvania was a must-win state for Trump.

The 77-year-old Biden was born in Scranton, Pennsylvania, and sought to contrast his working-class roots with the affluent Trump's by casting the race as "Scranton versus Park Avenue."

Biden's victory came after more than three days of uncertainty as election officials sorted through a surge of mail-in votes that delayed the processing of some ballots.

Four years ago, Trump breached the Democrats' "blue wall," narrowly winning Pennsylvania, Michigan and Wisconsin — a trio of Great Lakes states that had long served as a bulwark against Republican presidential candidates.

On Saturday, Democrat Joe Biden captured it back — and also won the presidency — after The Associated Press declared the former vice president the winner of his native Pennsylvania at 11:25 a.m. EST.

The AP called the race for Biden, who held a 30,952-vote lead after it determined that the remaining ballots left to be counted would not allow Trump to catch up. The news agency has already declared Biden the winner in both Michigan and Wisconsin.

Under Pennsylvania law, a recount is automatic when the margin between two candidates in a statewide race is less than 0.5 percentage points. Biden's lead over Trump was on track to stay outside of that margin as final votes are counted.

There are roughly 62,000 mail ballots remaining to be counted. Biden has won the overwhelming majority of mail ballots cast in the state.

Biden's win in Pennsylvania was a dramatic, though not unexpected, turn after Trump jumped out to an early Election Day lead of 675,000 votes and prematurely declared he had won the state.

Over coming days, as local elections officials tabulated more ballots, Trump's lead dropped sharply, with Biden winning roughly 75 percent of the mail-in vote between Wednesday and Friday, according to an analysis by the AP.

Another reason the late-breaking mail vote broke Biden's way: Under state law, elections officials are not allowed to process mail-in ballots until Election Day.

Biden, who was born in Scranton, claims favorite-son status in the state and has long played up the idea that he was Pennsylvania's "third senator" during his decades representing neighboring Delaware. He's also campaigned extensively in the state from his home in Delaware.