Political polarization is the worst it’s been since the Civil War, some experts argue. How did we get here? How have America’s ideologies shifted so much in the past four decades? What forces underlie the growing divide between Republicans and Democrats? And how has social media and varying sources of information widened the gap?

In episode 21, professors Julian Zelizer and Sam Wang discuss party polarization with Matt Grossman and David Hopkins, co-authors of the new book, “Asymmetric Politics: Ideological Republicans and Group Interest Democrats.” Published by Oxford University Press, the book provides a new understanding of contemporary polarization. Podcast Here