NetIn Talk by Balazs Lengyel

Social networks amplify inequalities by fundamental mechanisms of social tie formation such as homophily and triadic closure. These forces sharpen social segregation, which is reflected in a fragmented social network structure. Geographical impediments such as distance and physical or administrative boundaries also reinforce social segregation. In this talk, I give an overview of our recent work providing evidence that urban mobility, social network structure, and income inequalities are interrelated. Investigating online social networks, we find that fragmentation of social networks is higher in towns where residential neighborhoods are divided by physical boundaries such as railroads, major roads, or rivers. We show that these urban geography features have significant relationships with income inequality via social network fragmentation. Then, using geo-located Twitter data in the 50 largest metropolitan areas in the US, we illustrate that social networks of residents from relatively poor neighborhoods are spatially concentrated around the home. Those who commute to work to distant places may create ties that enrich their social capital. Traces of cell phone GPS coordinates, however, tell us that physical barriers in cities separate large shares of mobility. To mitigate urban inequalities, we need better access across barriers in cities and foster healthier social networks.

Link: Inequality is rising where social network segregation interacts with urban topology | Nature Communications