WASHINGTON — Who ends up in the White House for the next four years will be determined by the winning number of 270 electoral votes.

President Donald Trump carried the prized battleground of Florida, then he and Democrat Joe Biden shifted their focus early Wednesday to three northern industrial states — Wisconsin, Michigan and Pennsylvania — that could prove crucial in determining who wins the White House.

A late burst of votes in Michigan and Wisconsin gave Biden a small lead in those states, but they remain too early to call. Hundreds of thousands of votes were also outstanding in Pennsylvania.  

Voting was generally calm in the conclusion of an epic campaign that will shape America’s response to the surging coronavirus pandemic and foundational questions of economic fairness and racial justice.

Nearly 2.9 million more people voted for Hillary Clinton in the 2016 presidential election, but she still lost.

Trump won because he took the Electoral College, a system set up in the U.S. Constitution and refined through the centuries. This is where the magic number comes into play.

To win the White House, a candidate must win at least 270 electoral votes. That’s a majority of the 538 that are up for grabs in the 50 states.

Here’s a look at some of the possible paths to 270 for Trump and Biden. The scenarios listed below are current as of 9:30 a.m. ET.

Donald Trump

Based on current results as of 9:30 a.m., the easiest path to 270 includes Georgia, North Carolina and Pennsylvania. However, with thousands of votes not counted in Pennsylvania, that result would be unlikely for several days. If Trump wins those three states, he needs either Michigan or Wisconsin to pass 270 electoral votes.

Joe Biden

Biden has several paths to 270, but the most likely scenario for Biden to hold on to his lead in Nevada, Michigan and Wisconsin. If he wins those three states, he will reach 270 electoral votes.

Vote tabulations routinely continue beyond Election Day, and states largely set the rules for when the count has to end. In presidential elections, a key point is the date in December when presidential electors met. That’s set by federal law.

Several states allow mailed-in votes to be accepted after Election Day as long as they were postmarked by Tuesday. That includes Pennsylvania, where ballots postmarked by Nov. 3 can be accepted if they arrive up to three days after the election.

Pennsylvania Gov. Tom Wolf tweeted that his state had over 1 million ballots to be counted and that he “promised Pennsylvanians that we would count every vote, and that’s what we’re going to do.”

Trump appeared to suggest those ballots should not be counted, and that he would fight for that outcome at the high court. But legal experts were dubious of Trump’s declaration.

“I do not see a way that he could go directly to the Supreme Court to stop the counting of votes. There could be fights in specific states, and some of those could end up at the Supreme Court. But this is not the way things work,” said Rick Hasen, a professor of law and political science at the University of California-Irvine.

Trump has appointed three of the high court’s nine justices, including, most recently, Amy Coney Barrett.

Democrats typically outperform Republicans in mail voting, while the GOP looks to make up ground in Election Day turnout. That means the early margins between the candidates could be influenced by the type of votes — early or Election Day — being reported by the states.

Throughout the campaign, Trump cast doubt about the integrity of the election and repeatedly suggested that mail-in ballots should not be counted. Both campaigns had teams of lawyers at the ready to move into battleground states if there were legal challenges.

The tight overall contest reflected a deeply polarized nation struggling to respond to the worst health crisis in more than a century, with millions of lost jobs and a reckoning on racial injustice.

Trump kept several states, including Texas, Iowa and Ohio, where Biden had made a strong play in the final stages of the campaign. But Biden also picked off states where Trump sought to compete, including New Hampshire and Minnesota. But Florida was the biggest fiercely contested battleground on the map, with both campaigns battling over the 29 Electoral College votes that went to Trump.

The president adopted Florida as his new home state, wooed its Latino community, particularly Cuban-Americans, and held rallies there incessantly. For his part, Biden deployed his top surrogate — President Barack Obama — there twice in the campaign’s closing days and benefitted from a $100 million pledge in the state from Michael Bloomberg.

Democrats entered the night confident not only in Biden’s prospects, but also in the the party’s ability to take control of the Senate. But the GOP held several seats that were considered vulnerable, including in Iowa, Texas and Kansas. The House was expected to remain under Democratic control.

The coronavirus pandemic — and Trump’s handling of it — was the inescapable focus for 2020.

For Trump, the election stood as a judgment on his four years in office, a term in which he bent Washington to his will, challenged faith in its institutions and changed how America was viewed across the globe. Rarely trying to unite a country divided along lines of race and class, he has often acted as an insurgent against the government he led while undermining the nation’s scientists, bureaucracy and media.

The momentum from early voting carried into Election Day, as an energized electorate produced long lines at polling sites throughout the country. Turnout was higher than in 2016 in numerous counties, including all of Florida, nearly every county in North Carolina and more than 100 counties in both Georgia and Texas. That tally seemed sure to increase as more counties reported their turnout figures.

Voters braved worries of the coronavirus, threats of polling place intimidation and expectations of long lines caused by changes to voting systems, but appeared undeterred as turnout appeared it would easily surpass the 139 million ballots cast four years ago.

No major problems arose on Tuesday, outside the typical glitches of a presidential election: Some polling places opened late, robocalls provided false information to voters in Iowa and Michigan, and machines or software malfunctioned in some counties in the battleground states of Ohio, Pennsylvania, Georgia and Texas.

The cybersecurity agency at the Department of Homeland Security said there were no outward signs by midday of any malicious activity.

With the coronavirus now surging anew, voters ranked the pandemic and the economy as top concerns in the race between Trump and Biden, according to AP VoteCast, a national survey of the electorate.

Voters were especially likely to call the public health crisis the nation’s most important issue, with the economy following close behind. Fewer named health care, racism, law enforcement, immigration or climate change

The survey found that Trump’s leadership loomed large in voters’ decision-making. Nearly two-thirds of voters said their vote was about Trump — either for him or against him.

The Associated Press contributed to this report.