Why We're Polarized

In 1992, a study asked Americans a simple question: How would you feel if your child married someone from the other political party? Fewer than 5% of people in either party said they would be “somewhat or very unhappy” about it. By 2019, that number had skyrocketed. For Democrats, it jumped to 35%. For Republicans, it was an astonishing 45%. This is a transformation in social identity. The data reveals a phenomenon known as “affective polarization,” where political disagreement has morphed into genuine personal dislike. People aren't just disagreeing with the other side’s policies; they are beginning to fundamentally distrust, and even resent, the people on that side.

This dramatic change in social feeling is precisely what fascinated Ezra Klein. As a prominent journalist, co-founder of Vox, and host of a popular podcast, he had a front-row seat to the escalating tensions in American public life. For years, he observed that the old models for explaining political behavior—based on rational policy choices or demographic trends—were failing to capture the intense, emotional nature of modern partisanship. He noticed that the arguments were about who 'we' were and who 'they' were. This book emerged from his decade-long effort to understand the psychological machinery behind our divisions, exploring why good, reasonable people can be sorted into tribes that view each other with such suspicion.

Module 1: The Great Sorting

We often think of polarization as extremism. People's views get more radical. But Klein argues that's not the full story. The more powerful force at play is something different. It’s a process he calls "sorting."

Imagine American politics fifty years ago. The Democratic and Republican parties were ideologically messy. You had conservative Democrats from the South. You had liberal Republicans from the Northeast. A voter in 1976 might have struggled to tell you which party was more conservative. This ideological overlap forced compromise. It lowered the stakes of any single election.

Then, something changed. A half-century of political, demographic, and cultural shifts sorted Americans into two distinct, homogeneous parties. This is the "Great Sorting." It’s about everything. Race, religion, geography, even our personalities and consumer choices have all aligned with our political affiliation.

Think about it this way. In 1952, only 6% of Democrats were nonwhite. By 2012, that number was 43%. Today, the Democratic coalition is a mix of racial, religious, and social groups. The Republican party, in contrast, has become the party of white Christians. This sorting is also geographic. As author Bill Bishop noted in The Big Sort, we increasingly live in politically homogeneous communities. The share of Americans living in "landslide counties," where one presidential candidate wins by 20 points or more, has skyrocketed.

So here's what that means for you. The person you disagree with politically is now more likely to be different from you in almost every other way. They likely live in a different kind of place, worship differently, and even shop at different stores. This transforms political disagreement into something that feels much more personal. It feels like a clash of cultures. A clash of identities.

This leads to a powerful, and often destructive, dynamic. "Negative partisanship" now drives our political behavior more than loyalty to our own party. Research shows our feelings toward the opposing party have plummeted. We are motivated more by our fear and distrust of "them" than by our love for "us." In a 2016 Pew poll, majorities of voters said a primary reason for their choice was that the other party’s policies were bad for the country. This is why a candidate like Donald Trump, who was disliked by many in his own party, could still command their vote. The alternative was simply seen as worse.

And here’s the thing. This sorting makes partisans seem more rational. As the parties become more distinct, it becomes easier for voters to see the differences and pick a side. In the 1970s, you needed to be a political junkie to know where the parties stood on every issue. Today, the differences are so stark that even casual observers can see them. A vote for a Democrat today means a vote for a clear set of policies on healthcare, climate, and social issues. A vote for a Republican means a vote for a distinctly different set. This clarity raises the stakes of every election. It turns politics into a zero-sum battle for the soul of the country.