What’s Your Ideal Community? The Answer Is Political

The American political map that has emerged over the last half-century, with blue cities and red beyond, is a product of both the ideological realignment of the two parties and geographic sorting among voters. It also raises a fascinating question about how our politics are shaped by where we live.

Is it simply that people who are already liberal choose dense urban environments and conservatives choose more suburban living? Or do these places influence how we feel about government — and each other — in ways that make us more liberal or conservative?

Political scientists, fortunately, cannot randomly assign people to cities, suburbs or rural outposts and then wait to see if their politics adapt. But their theories of why density might matter for partisanship add a provocative layer to how we think about the differences among us that are more often defined in an election year by education, income or race.

A large Pew survey two years ago of American political life found that self-described liberals overwhelmingly said they’d prefer to live where the homes are smaller and closer together but where the amenities are within walking distance. Conservatives chose the opposite trade-off: big homes, spaced farther apart, but with schools and restaurants miles away. The question got at a pattern underlying politics today: Beyond our disagreements about taxes, welfare or health care, partisans also fundamentally favor different kinds of places.

Like the pattern linking education and politics, this one is a bit of a mystery.

“There is something really kind of strange and interesting about the connection between peoples’ preferences — what they view as the good life, where they want to live — and their partisanship,” said Jonathan Rodden, a political scientist at Stanford. His precinct-level maps of presidential election results show deep blue in the densest, central parts of metropolitan areas, where you’d find the Main Streets, city halls, rowhouses and apartment buildings. The farther you travel from there, the redder the precincts become. And this is true whether you look around New York City or Terre Haute, Ind.

Answers to another Pew question from that 2014 survey show the same. It asked people about their preferences and not their current addresses.

Other survey data suggests this divergence has existed for decades, whether you ask people how they’d like to live or where they actually do. Conversely, ask them about their politics, and an underlying picture emerges about where (and how) they live.

What befuddles even political scientists is whether we’re looking here at a treatment or a selection effect — or how much of each is operating. Have Clinton supporters self-selected into dense places (for reasons that may have little to do with density itself), or is the experience of living in a dense area a kind of treatment that has altered their politics?

“How would we ever figure that out empirically?” Mr. Rodden said. “Because we know that sorting is also happening. We know if you grow up gay in rural Nebraska, and you’re looking for ways out, you might start in Omaha and end up in New York City.”

Thomas Ogorzalek, a political scientist at Northwestern, argues that liberalism has its roots in big-city governments trying to solve the kinds of local problems that arise when diverse populations cram together. Compared with the suburbs or rural America, cities are more complex. They’re harder to govern, which means in many ways that they demand bigger government: a large transit agency to move people around, intricate parking rules to govern scarce spaces, a garbage truck armada to keep the streets clean.

“Externalities accumulate faster in dense places, and you need to do something about them,” Mr. Ogorzalek said. In other words, the trash piles up.

New York City, with its 24,000 restaurants and bars, needs a system of publicly posted health grades. A town with two restaurants may not. New York needs some colossal bridges connecting Manhattan and Brooklyn. A smaller community doesn’t need public-works projects on that scale. New York requires a large police force. A rural resident may need self-reliance when the closest officer is 10 miles away.

It’s conceivable that people who live in cities come to value more active government. Or they’re more receptive to investing in welfare because they pass the homeless every day. Or they appreciate immigration because their cab rides and lunch depend on immigrants. This argument is partly about the people we’re exposed to in cities (the poor, foreigners), and partly about the logistics of living there.

“As someone who’s lived in cities for almost all of my adult life, it’s impossible to conceive of a well-functioning city without a strong public works and a strong governmental infrastructure,” said Thomas Sugrue, a historian at New York University. Government has actively shaped suburbia, too, for example engineering the mortgage tax breaks that make owning large homes more affordable. But those government interventions are often less visible. “They’re not invisible,” Mr. Sugrue said, “when you’re going down Eighth Street as it’s being repaved and the sewer lines underneath it are being replaced.”

The political analyst William Schneider articulated a similarly plausible idea about the politics of suburbia in a classic 1992 article for The Atlantic. As cities require reliance on the commons, Mr. Schneider argued, “to move to the suburbs is to express a preference for the private over the public.” The suburbs entail private yards over public parks, private cars over public transit, private malls over public squares. Suburban living even buys a kind of private government, Mr. Schneider wrote, with the promise of local control of neighborhood schools and social services that benefit only the people who can afford to live there.

His theory supports self-selection; people who want that environment move to it. But Jessica Trounstine, a political scientist at the University of California, Merced, believes that people who move to the suburbs, apolitically, can also become part of a political ideology that they find benefits them and their pocketbooks.

Nature acts, she argued. And although researchers can’t geographically shuffle people to prove this, they can try in modest ways to alter the context around us. Ryan Enos, a Harvard political scientist, has simulated the effects of added diversity in white suburbs by hiring Spanish speakers to board commuter trains outside Boston. It looked as if immigrants had moved into the neighborhood. Commuters who seemed alarmed at first (and more hostile to immigration as a result) later grew more at ease with their new fellow passengers.

“There are a lot of things we can experiment on, but context in itself is this widely diffuse and complex thing,” Mr. Enos said. Nailing down how we’re shaped by it, he said, “is the most impossible problem in social science.”