Social interactions are considered pivotal to agglomeration economies. We explore a unique dataset on mobile phone calls to examine how distance and population density shape the structure of social interactions. Exploiting an exogenous change in travel times, we show that distance is highly...

We study the dual relationship between market structure and prices and between market structure and investment in mobile telecommunications. Using a uniquely constructed panel of mobile operators' prices and accounting information across 33 OECD countries between 2002 and 2014, we document that...