We introduce, analyze, and describe subnational data on cross-gender friendships for nearly 200 countries and territories, using data from 1.38 trillion ties between 1.8 billion Facebook users. Homophily by gender exists nearly everywhere, with individuals' strongest ties exhibiting less...

We use anonymized and aggregated data from Facebook to show that areas with stronger social ties to two early COVID-19 “hotspots” (Westchester County, NY, in the U.S. and Lodi province in Italy) generally have more confirmed COVID-19 cases as of March 30, 2020. These relationships hold after...

We introduce a new measure of social connectedness between U.S. county-pairs, as well as between U.S. counties and foreign countries. Our measure, which we call the "Social Connectedness Index" (SCI), is based on the number of friendship links on Facebook, the world's largest online social...

We use anonymized data from Facebook to construct a new measure of the pairwise social connectedness between 180 countries and 332 European regions. We find that two countries trade more with each other when they are more socially connected and when they share social connections with a similar...

We use anonymized and aggregated data from Facebook to explore the spatial structure of social networks in the New York metro area. We highlight the importance of transportation infrastructure in shaping urban social networks by showing that travel time and travel costs are substantially...

We use anonymized and aggregated data from Facebook to explore the spatial structure of social networks in the New York metro area. We highlight the importance of transportation infrastructure in shaping urban social networks by showingthat travel time and travel costs are substantially stronger...