We use aggregated data from Facebook to show that COVID-19 was more likely to spread between regions with stronger social network connections. Areas with more social ties to two early COVID-19 “hotspots” (Westchester County, NY, in the U.S. and Lodi province in Italy) generally had more...

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 document that the recent house price experiences within an individual's social network affect her perceptions of the attractiveness of property investments, and through this channel have large effects on her housing market activity. Our data combine anonymized social network information from...

In this paper, we investigate political communications in social networks characterized both by homophily–a tendency to associate with similar individuals–and group size. To generate testable hypotheses, we develop a simple theory of information diffusion in social networks with homophily...

We study why acquisitions of entrant firms by an incumbent can deter innovation and entry in the digital platform industry, where there are strong network externalities and some customers face switching costs. A high probability of an acquisition induces some potential early adopters to wait for...

We explore the links between social capital and labor market networks at the neighborhood level. We harness rich data taken from multiple sources, including matched employer-employee data with which we measure the strength of labor market networks, data on behavior such as voting patterns that...

Networking and the giving and receiving of advice outside of one's own firm are important features of entrepreneurship and innovation. We study how immigrants and natives utilize the potential networking opportunities provided by CIC, formerly known as the Cambridge Innovation Center. CIC is...

We study factors influencing individuals' decisions to purchase Citibank stock during the 1920s. Ownership was encouraged by proximity to New York and higher wealth. Lack of familiarity was also an important barrier. The establishment of Citibank branches within a U.S. county or a foreign...

This appendix contains additional figures and tables referenced in the paper, but not included in the main figures and tables. It contains the geographic distribution of shareholders and a visualization of the business network. It includes alternative specifications for the county-level and...

Many economic activities are embedded in networks: sets of agents and the (often) rivalrous relationships connecting them to one another. Input sourcing by firms, interbank lending, scientific research, and job search are four examples, among many, of networked economic activities. Motivated by...