The Democratic nominee only needed one more major swing state to secure the White House after obtaining the votes required to win Michigan, with a win in neighbouring Wisconsin announced by the Associated Press earlier on Wednesday. It was also reported by the Associated Press that Mr Biden had won Arizona early on Wednesday morning.
Michigan was Mr Trump’s narrowest statewide victory over Hillary Clinton in 2016, and he has repeatedly expressed his pride in winning it from the Democrats.
Follow live: 2020 election results, updates and analysis
As in 2016, he held his last rally of the campaign in the city of Grand Rapids on Monday night.
But Mr Biden polled well in Michigan throughout the general election campaign as he worked hard to target so-called rust belt states where Mr Trump previously won over scores of blue-collar white voters.
Ms Clinton lost Michigan partly because of these voters, but also because of anaemic turnout in typically solid Democratic areas in the city’s suburbs and cities.
Turnout in Detroit exceeded 2016 numbers, with the city and neighbouring counties favouring the former vice president by more than 500,000 votes.
But key to his 2020 victory was a significant surge in mail-in voting in the state, with more than 3 million ballots cast by mail.
In the weeks before Election Day, Michigan saw a protracted legal battle over deadlines for mail-in ballots that arrived as polls had closed.
Absentee ballots that arrived after 8pm on Wednesday were rendered ineligible to be counted, and state officials mounted an effort to encourage voters to post theirs in as soon as possible or else drop them off in person.
Mr Trump has spent the year feuding with Michigan’s Democratic governor, Gretchen Whitmer, over her criticism of his administration’s response to the coronavirus pandemic and her decision to put her state under tough lockdown measures.
The governor was later the subject of an alleged kidnap plot by a self-styled right-wing, anti-government militia group, which was foiled by the FBI and state law enforcement agencies. In the aftermath, she condemned the president for provoking his supporters to threaten elected officials during the pandemic; Mr Trump responded by accusing her of ingratitude.
Mr Trump told supporters to “liberate” several states with Democratic governors, as anti-"lockdown" protests were mounted amid the pandemic that has killed more than 231,000 Americans and infected more than 9 million others.
Michigan health officials have confirmed more than 192,000 cases in the state since the onset of the outbreak, with a death toll at more than 7,400, as of Wednesday.
Wednesday’s single-day case count – 4,101 – is the highest-ever, breaking a record previously set just days ago, when 3,792 cases were reported on 31 October.
His campaign will attempt to launch additional legal challenge across critical swing states, including Michigan, arguing that his campaign was not allowed “meaningful access” to observe vote counts.
He also demanded a recount in Wisconsin, where Mr Biden carried a slim 20,000-vote lead, or less than 1 per cent, with nearly all votes accounted for.
"I’m not here to declare we won," Mr Biden said from Delaware on Wednesday afternoon. “But I believe when the count is done, we will be declared the winner.”
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