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...

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 article, we review the expanding body of economic research on...