Will improvements in information technology eliminate face-to- face interactions and make cities obsolete? In this paper, we present a model where individuals make contacts and choose whether to use electronic or face-to-face meetings in their interactions. Cities are modeled as a means of...

The fast and often chaotic urbanization of the developing world generates both economic opportunity and challenges, like contagious disease and congestion, because proximity increases both positive and negative externalities. In this paper, we review the expanding body of economic research on...