In this new paper, I weave recent research in political science, economics, psychology and more into an account of political polarization and the rise of populist nationalism as a surprising and overlooked side-effect of urbanization.
I claim that we've failed to fully grasp that urbanization is a relentless, glacial social force that transforms entire societies and, in the process, generates cultural and political polarization by segregating populations along the lines of the traits that make individuals more or less responsive to the incentives that draw people to the city. I explore three such traits — ethnicity, ideology-correlated aspects of personality, and level of educational achievement — and their intricate web of relationships. The upshot is that, over the course of millions of moves over many decades, high density areas have become economically thriving multicultural havens while whiter, lower density places are facing stagnation and decline as their populations have become increasingly uniform in terms of socially conservative personality, aversion to diversity, and lower levels of education. This self-segregation of the population, I argue, created the polarized economic and cultural conditions that led to populist backlash.
Because the story of urbanization just is the story of a strengthening relationship between density, human capital and economic productivity, it's also the story of relative small town and rural decline. The same process that has filtered better-educated, more temperamentally liberal whites out of lower density places has left those places with less vibrant economies, but also with more place-bound, ethnocentric populations.