The state-by-state votes, traditionally an afterthought, have taken on outsized significance this year in light of Trump's unprecedented assault on the nation's democratic process. Pushing false claims of widespread fraud, Trump has pressured state officials to throw the election results out and declare him the winner.
In the United States, a candidate becomes president not by winning a majority of the national popular vote but through an electoral college system, which allots electoral votes to the 50 states and the District of Columbia largely based on their population.
Biden, the Democratic former vice-president, won 306 of the 538 electoral votes available - exceeding the necessary 270. Trump, a Republican, earned 232.
In capitals such as Lansing, Michigan; Harrisburg, Pennsylvania; and Atlanta, Georgia, electors - typically party loyalists - will gather to formally cast those votes on Monday.
While there are sometimes a handful of "rogue" electors who vote for someone other than the winner of their state's popular vote, the vast majority rubber-stamp their state's results.
Trump has called on Republican state legislators to appoint their own electors, essentially ignoring the will of the voters. State lawmakers have largely dismissed the idea.
The votes cast on Monday will be sent to Congress to be officially counted on January 6, the final stage of America's complex election process.
Trump said late last month he would leave the White House if the electoral college voted for Biden, but has since pressed on with his unprecedented campaign to overturn his defeat, filing numerous failed lawsuits challenging state vote counts. On Friday, the US Supreme Court dismissed a lawsuit filed by Texas that sought to invalidate the results in four states that Biden won.
Speaking to Fox News at the weekend, Trump asserted the election dispute was "not over" and "we're going to continue to go forward".
Once the electoral college vote is complete, Trump's sole remaining gambit would be to convince Congress not to certify the count on January 6. Federal law allows lawmakers to challenge states' electoral votes, which prompts both the House of Representatives and the Senate to debate the objections before voting on whether to sustain them.
Mo Brooks, a conservative Republican congressman, has vowed to file challenges when Congress reviews the vote next month, though it is all but certain both chambers would reject his effort. Democrats control the House, while several moderate Republicans in the Senate have already publicly accepted Biden's victory.
While the electoral votes usually involve some pomp and circumstance, most events this year will be significantly scaled back due to the coronavirus pandemic.