Last week’s British election illustrated one of the most remarkable developments in recent elections: the propensity of younger generations not only to vote but also to vote overwhelming for older socialist leaders advocating left-wing economic policies last fashionable during the 1970s.

This cleavage between younger and older voters seems to have replaced social class, which has been a long-standing cleavage in British politics. One key factor is the substantial division between young and old voters over cultural values. Here’s what the data show us.

There’s a growing age gap in U.K. and U.S. voting

In the U.K., the Conservative Party has done better among older voters than younger voters for decades. But the age gap has expanded recently — first in the June 2016 Brexit referendum, where two-thirds of those under 35 voted against leaving the European Union, while 57 percent of those 64 and older (also known as “pensioners”) voted to leave.

Similar divisions persisted in the 2017 general election. According to the Ashcroft General Election Day poll, two-thirds (67 percent) of 18- to 24-year-olds supported Labour compared to 23 percent of pensioners. By contrast, only 18 percent of 18- to 24-year-olds supported the Conservatives compared to 59 percent of pensioners.

The number of young people who turned out to vote is still to be determined with official data. But the fraction who registered to vote increased sharply. Moreover, at least some data, that of Sky News, suggest that turnout among 18- to 24-year-olds increased from 43 percent in 2015 to 66 percent in 2017.

The support of young people for Labour and its leader, Jeremy Corbyn, echoes the 2016 Democratic primary in the U.S. Sen. Bernie Sanders is similar to Corbyn in key respects — both are older white men, both advocate socialist politics. Sanders also did much better than Hillary Clinton among younger voters.

The age gap persisted in U.S. general election. According to the American National Election Studies, among major-party voters Clinton won 18- to 24-year-olds by a 64-36 percent margin, but lost 47-53 percent among those 65 and older.

What is driving the age gap?

One possibility is that younger voters are attracted to the egalitarian economic message of leaders like Corbyn and Sanders. Younger generations may feel that they face more limited economic opportunities than their parents and grandparents, given levels of student debt, lack of secure jobs, stagnant wages, and youth unemployment.

Another possibility is that younger voters in Britain were motivated more by liberalism on cultural issues such as LGBTQ rights, women’s equality, globalization, and climate change, as well as opposition to the nationalist and anti-immigration themes of Theresa May and Donald Trump. Data from the World Values Survey shows persistent generation gaps in support for gender equality, secularization, gay rights, and global governance.

This same pattern was evident in last week’s U.K. election. The Election Day poll asked respondents to assess whether several things were forces for good or ill in society. As you can see in the graph below, young people were more likely than older people to say that all of these were a force for good: the Internet, environmentalism, feminism, multiculturalism, globalization, and immigration. The only item where this pattern was reversed was capitalism.

Public opinion toward economic issues shows similar substantial age gaps:

Young people were also more left wing in their attitudes toward social mobility, wealth redistribution, immigration, and rights to health care, housing and education. In all these regards, young people in the U.K. are more likely to be attracted to Labour’s economic policies.

Finally, because young people have grown up during the era of austerity, with funding cuts in education and the National Health Service, they might be more pessimistic about than their parents, who came of age in more prosperous times. But age gaps were much smaller when respondents were asked whether about life prospects, social change, and opportunities for advancement and social mobility.

Overall, the 2016 U.S. election, the Brexit referendum, and the 2017 U.K. election show a growing salience of age — one that seems to be displacing traditional cleavages based on occupation and social class. If these persist — and if young people can be mobilized to vote — this age gap may help to transform the policy agenda, the future of party competition, and the prospects of long-term electoral change.

Pippa Norris is the McGuire Lecturer in Comparative Politics at Harvard University, professor of government and international relations at the University of Sydney, and director of the Electoral Integrity Project. Her recent books include “Why Electoral Integrity Matters” (Cambridge University Press, 2014), “Why Elections Fail” (Cambridge University Press, 2016) and “Strengthening Electoral Integrity” (Cambridge University Press, 2017). She is working on a book with Ron Inglehart entitled “Cultural Backlash: The Rise of Populism.”