One of the trends we are going to be watching after Election Day is how educational polarization might have intensified among the American electorate. The Republican Party currently holds a six-point lead over the Democratic Party in voter preference among registered voters without a college degree, while the Democrats have a 13-point advantage among those with at least a bachelor's degree, according to Pew Research. This is a marked reversal from dominant voting patterns not even 20 years ago, when Republicans were predominantly viewed as the party of the wealthy and Democrats the party of the working class.

This divide has fundamentally reshaped our politics in recent years. Think of the Republican Party's embrace of anti-expert views on topics like vaccination or climate change or the wider conflict over teaching about race and gender in schools. These culture war issues — which also stem from a growing diploma divide, where higher educational attainment is increasingly aligned with liberal political values — have changed what issues our political parties prioritize, how they operate and which voters they try to win.

Recently, the 538 Politics podcast interviewed Matt Grossman and David Hopkins, political scientists and authors of "Polarized by Degrees: How the Diploma Divide and the Culture War Transformed American Politics." To hear their takes on this trend, check out the podcast here.

For decades, Wisconsin was a key brick in Democrats' "blue wall": It voted for the Democratic presidential candidate in every election from 1992 to 2012. But in 2016, that streak snapped: Trump won Wisconsin by 0.8 percentage points, helping propel him to the presidency.

Democrats flipped Wisconsin back in 2020, but Biden won it by only 0.6 points. And polls suggest 2024 could be the third consecutive presidential election in which Wisconsin is decided by less than 1 point. According to 538's final polling average of the state, Harris leads Trump by just 1.0 points.

If you dig into the crosstabs of those polls, it looks like Wisconsin is experiencing the same demographic trends as the rest of the country: White voters are getting more Democratic, while voters of color are getting more Republican. According to an average of crosstabs of Wisconsin polls conducted Sept. 18-Oct. 18, white Wisconsinites were supporting Trump by 1 point. But according to exit polls, they supported Trump in the 2020 election by 6 points. By contrast, according to crosstabs of Black and Hispanic Wisconsinites, those two groups had shifted toward Trump by more than 20 points each!

But there are two big caveats to this. The first is that Wisconsin's nonwhite population is pretty small. The state's citizen voting-age population is 86% white, 5% Black and 4% Hispanic. This makes it the whitest of the seven main swing states — meaning that any racial voting shifts in the 2024 election will have a muted impact here.

The second caveat is that, with such small Black and Hispanic populations, it's hard for pollsters to get a big enough sample of these voters in Wisconsin. That makes their Black and Hispanic crosstabs subject to a high amount of error.

More important in Wisconsin is the education gap. About one-third of Wisconsinites over age 25 have at least a bachelor's degree, while the remaining two-thirds do not. In 2020, Trump won non-college-educated voters in Wisconsin by 6 points, but Biden won college-educated Wisconsinites by 16 points.

Mary pointed out that there are some indications that polls could be overstating Harris' weakness with Black voters due to the difficulties in getting a representative sample among those voters. I wanted to add that polling is challenging in general, and polling Black voters is especially so.

After an election, pollsters calibrate for the future based on actual election results. But individual votes are of course private, so there's no gold standard that tells us how voters from certain demographic groups — including Black Americans — voted. And when pollsters do recalibrate after an election, they are far more likely to focus on the more numerous white voters.

It's also harder to recruit representative samples of Black voters in the first place. I recently co-authored an article, "Getting the Race Wrong," discussing the online and in-person surveys we conducted here in Philadelphia during the 2023 Democratic mayoral primary. In that race, our polls mirrored the public polls, getting the levels of support for Rebecca Rhynhart (the city's controller, who had significant support from Center City’s liberal neighborhoods) and Helen Gym (an at-large city councilmember who campaigned with Bernie Sanders and drew support from Philadelphia's most progressive neighborhoods) close to right.

But like the public polls, we significantly understated the support for the eventual winner, Cherelle Parker, a former city councilmember and state House representative. A big part of the reason why is that Parker dominated in Philadelphia's majority Black neighborhoods, in a city whose Democratic electorate is majority Black. Even when we upweighted the Black respondents who participated in our survey, our polls understated her support, in part because our Black respondents were significantly more likely to have a college degree than the general population of Black voters here in Philadelphia.

Throughout this year, we've been tracking how both Trump and Harris have been performing with key demographic groups. And we've seen a common trend emerge over the last few months: In polls, Harris appears to be improving upon Biden's 2020 performance among older voters and white voters, and losing ground among younger voters and voters of color. The latest round of polling before the election appears to continue the trend.

Harris is polling, on the margin, 6 percentage points better than Biden's 2020 performance among white voters, while she's lost support among Black voters and Hispanic voters. But white voters make up a much higher percentage of the electorate than other demographic groups: 67% of voters in 2020 identified as white, according to the 2020 exit polls. And in the key northern battleground states of Michigan, Wisconsin and Pennsylvania, the white share of the electorate is even larger — 81% in Michigan and Pennsylvania and 86% in Wisconsin. This may explain some of the trends we've seen in the polls over the last few months, where Harris performs better in these three states than in the other swing states.

However, there is some indication that the national polls could be overestimating Harris' relative weakness among voters of color. We've seen some polls conducted specifically among Black and Hispanic voters that show less movement towards Republicans. Polls like these can sometimes be more reliable, as they are able to get a more representative sample of voters that may be difficult to reach for national surveys.

-Mary Radcliffe