David Grusky, Stanford University

Title: Social Class, Sushi, and Interaction

Abstract: Do people who are well-off come into frequent contact with people who are poor? Although it’s well-known that income inequality has grown dramatically over the last half-century, we don’t know as much about the amount of contact between people having more or less money. The key obstacle to measuring such “interaction segregation” has been wholly methodological: We’ve lacked the capacity to track real-life interactions among people as they move around their neighborhoods or go to work, school, and places of leisure. Because cell phones are now ubiquitous, it’s become possible for the first time to measure such interactions in real time, across the United States, and throughout the day. We proceed by analyzing 1.6 billion “interactions” (i.e., co-located cellphones) and infer the economic standing of their users from home addresses (based on cell phone location at night). The resulting map of U.S. interaction segregation shows that, because large cities can support venues (e.g., restaurants, shopping centers) that are targeted to thin socioeconomic slices of the population, contemporary urban life has become a homophily-generating machine.