A new study of 2020 voters found that President Biden expanded the Democratic base by attracting newer and younger voters while blunting former President Trump’s advantages among key groups that have historically favored Republican candidates.

The report, compiled by the Pew Research Center and published Wednesday, revealed that many groups once considered a cornerstone of either party’s coalition are now dividing their votes more evenly — a sign of a widening political spectrum in which polarization cuts across traditionally hardened demographic lines.

The voting analysis shows Biden held on to much of the coalition that former Secretary of State Hillary Clinton built in 2016: He matched or ran close to her support among women, Black and Asian Americans and millennials.

Biden improved dramatically over Clinton among suburban voters and those who see themselves as independents.

In 2016, Trump beat Clinton among suburban voters by a narrow 47 percent to 45 percent margin, the Pew data shows. Biden, however, ran up a huge 54 percent to 43 percent victory in those areas last year. Trump offset some of those losses by improving his vote share among urban voters by 9 percentage points and among rural voters by 6 points, but the plurality of Americans live in suburban areas that delivered a White House victory to Biden.

Overall, 55 percent of Biden’s votes came from the suburbs, a 7-point improvement over Clinton’s showing four years earlier. Just 48 percent of Trump’s vote came from the suburbs, down 5 points from 2016.

“Suburban votes, once the mainstay of Republican support, shifted toward Biden in 2020,” said William Frey, a demographer at the Brookings Institution.

Both Trump and Biden improved on their party’s performance four years earlier with their own voters — Trump captured 92 percent of Republican voters, up 3 points, and Biden carried 94 percent of Democrats, up 5 points from Clinton’s level of support.

Voters who resist aligning themselves with one of the two major parties made a substantial difference. Where many of those voters opted for a third-party candidate in 2016, this past year they picked a side.

Trump narrowly carried voters who saw themselves as independent in 2016, by a single percentage point. His share among those voters remained unchanged four years later, at 43 percent.

Biden’s vote share among independents rocketed 10 points over Clinton’s showing, to 52 percent.

The survey shows a changing of the generational guard in an electorate that now reflects more influence for the younger millennial and Z generations. Just 44 percent of voters were members of the baby boom or silent generations, the first time in decades that those groups have made up less than half the electorate.

Millennials and members of Generation Z, born after 1996, backed Biden by a 20-point margin. Baby boomers favored Trump by 3 points, almost identical to his 4-point edge in 2016, while members of the silent generation — those who are between the ages of 76 and 93 — backed Trump by 16 points, a 3-point slide toward Biden from four years ago.

“We’ve reached peak baby boomer,” said Michael McDonald, a political scientist at the University of Florida. “At this point moving forward, we’re going to start seeing baby boomers’ turnout rates declining as they get into their twilight years.”

Nearly half, 49 percent, of voters who cast a ballot for Biden were under 50 years old, about the same score Clinton achieved. Just 38 percent of Trump’s vote came from voters in that age group.

Much of the new data shows starker polarization even among groups that used to overwhelmingly favor one side or the other.

Though millennials gave Biden more of their vote share than they had given Clinton four years ago, Trump improved his own performance by a whopping 8 points among that generation. Trump’s vote share grew among women by 5 points, among Hispanic Americans by 10 points and among white voters with a college degree by 4 points.

Biden, on the other hand, improved over Clinton’s performance among some traditionally Republican cohorts: He performed 8 points better among white men, 5 points better among white voters without a college degree and 5 points better among Catholic voters. Biden even doubled the share of the vote Clinton received among self-described moderate or liberal Republicans, from 8 percent to 16 percent.

A part of both candidates’ improvements over four years ago came from the lack of a prominent third-party contender who could peel off votes. In 2016, Green Party nominee Jill Stein, Libertarian Gary Johnson and Independent Evan McMullin took substantial shares of the vote; third-party candidates last year garnered about a third of the vote secured by their 2016 predecessors.

Those who voted for a third party in 2016 largely broke for Biden last year. He won those voters by a 53 percent to 36 percent margin, while the remaining 10 percent stuck with a nonmajor party candidate.

Both Biden and Trump succeeded in broadening the electorate as a whole: A whopping 19 percent of voters who cast ballots in 2020 had not voted in either 2016 or the 2018 midterm elections. Biden narrowly won those voters by a 49 percent to 47 percent margin, a sign that Trump’s campaign identified and turned out their own new voters.

But among those voters is a significant gap, one that could have ramifications for future elections: Voters under 30 who voted last year but not in the two prior elections backed Biden 59 percent to 33 percent; those people, who are earlier in their voting careers, are more likely to become regular voters than the first-time voters over 30, who backed Trump 55 percent to 42 percent.

“It’s important to know that the younger group of these voters went solidly for Biden,” Frey said. “Because this is a group that is far more racially diverse than older voters, it suggests that issues surrounding racial justice, Black Lives Matter and immigrant rights helped to activate these young people in ways that aided Biden and will likely help benefit Democrats in general if they can continue to engage these voting blocs.”