Social Capital in a Divided America: The Relationship between Economic Bridging and Affective Polarization

Does political polarization decline as relational bridges are built between people from different social and economic backgrounds? Circumstantial evidence supports the existence of a relationship: social capital has declined during the same period that affective polarization has risen. To date, though, we have lacked data to test whether the two are, in fact, dynamically related. In this article, I measure the extent of bridging social capital among people within zip codes, generated from 21 billion Facebook friendships of 72.2 million Americans. Using two measures of affective polarization—feeling thermometers and partisan traits—the analysis shows that people who live in communities with more economic bridging are less affectively polarized and that conversations among people who have different political views is a possible causal mechanism. These effects are more pronounced for the affluent and for Republicans—and for affluent Republicans most of all.