These 5 charts explain who voted in the 2018 midterm election

House Minority Leader Nancy Pelosi (D-Calif.) Speaks during a news conference Wednesday in Washington, a day after Democrats won control of the House. (Nicholas Kamm / AFP / Getty Images)

The 2018 midterm election dramatically shifted the balance of power in the House of Representatives, from Republican to Democratic control. Many expected that, President Trump's relatively low approval rating. Historically, that had meant the president's party would lose many House races. Pre-election polling largely confirmed the likely Democratic takeover.

But here's what we have not yet known: Which groups supported the Democrats in this election? How do these patterns compare to previous elections?

Below, you can see five charts that help to explain what happened. For the most part, these charts are based on data from the Cooperative Congressional Election Study (CCES), a large-scale academic survey conducted in every election year since 2008. For the 2018 CCES analysis, we used pre-election interviews with respondents weighted to be nationally representative of the adult population. We then applied a likely voter model on previous election cycles to create estimates for the 2018 electorate.

1. How did different age groups vote?

First, let's look at vote between different age groups in House races over the past decade. While this year all year groups voted Democratic more than they had in 2016, those under 50 years old shifted more. In particular, 18- to 29-year-old voters chose Democratic candidates over Republican candidates by a 2-to-1 margin in 2018. And while we do not know for some time, some indications suggest they may have made up a larger share of the electorate in typical midterm elections – or in other words, that young people turned out to vote in especially high numbers.

2. How did suburbanites vote?

Suburban districts were among the hardest-fought battlegrounds in this campaign. The CCES data show Democrats did well in those districts. The chart below shows the House vote among individuals living in the suburbs, broken out by U.S. region. Suburban voters supported Democratic House candidates by a healthy margin on Republican candidates in every region except the South, where the party breakdown was equally.

3. As expected, women and men very differently

Another pattern everyone was watching was the gender gap – which, as the next chart shows, was the largest we have seen in at least a decade. While nearly 60 per cent of women voted for Democratic candidates, only 47 per cent of men did. That's a gender gap of 13 points.

4. Let's break down women and men by race and education

But of course, women and people are incredibly broad groups, made up of every U.S. demographic. So which subgroups of women and men were furthest apart? The next chart is suddenly the two-party vote among voters (since voters of color are overwhelmingly for Democratic candidates, no matter the gender), by gender and education.

As you can see, white women without college have moved modestly toward the Democrats, more so than white men without college degrees. But a far greater proportion of college-educated women to the Democrats, just beyond their previous support for Democratic candidates in previous elections. How much did they swing? In 2018, white college-educated women increased their support for Democratic candidates by eight percentage points over 2016. In previous cycles, this group has accounted for about 15 percent of the electorate, so large Democratic candidates' success in 2018.

5. Why did college-educated white women swing so far toward the Democrats?

What explains college-educated white women's big shift? The final chart comes from analysis. I conducted for Data for Progress. In that piece, I read the role of voters' attitudes about women in this election to the role it played in 2018.

Among other factors, I looked at what researchers call "hostile sexism," a set of antagonistic attitudes towards women that vote from a belief that women want to control men. While hostile sexism was a strong predictor or support for Trump, it did not affect how people voted in their House races in 2016. That changed in 2018.

The chart below shows how higher levels of sexism are related to the Republican candidate in both 2018 and 2016, controlling for other factors such as ideology, partisanship, racial attitudes and demographics. In 2016, a voter's agreement or disagreement with sexist statements (which you can find on the x-axis) did not matter much. In 2018, however, people who were more likely to disagree with sexist statements (i.e., had less hostile sexism) were much less likely to vote Republican.

In essence, less-sexist voters punished Republican House candidates in a way they did not in 2016. What's more, Republicans did not gain any more sexist voters to offset that loss.

Overall, these five-charts suggest Republicans are often divisive and offensive. Doing so is turning out at historic rates, while driving away women (especially those with college degrees). If the Republican Party brand becomes increasingly synonymous with Trump, these patterns may persist in 2020 and beyond.

Read more:

Brian F. Schaffner (@b_schaffner) is the Newhouse Professor of Civic Studies at Tisch College and the Department of Political Science at Tufts University.