The number of people buying and selling products online in China has grown from practically zero in 2000 to more than 400 million by 2015. Most of this growth has occurred in cities. In this context, the Chinese government recently announced the expansion of e-commerce to the countryside as a...

This paper proposes a micro-foundation for knowledge spillovers. I model a city in which free knowledge transfers are bids by experts to entrepreneurs who auction jobs. These knowledge bids resemble a consultant's pitch to a potential client. Two fundamental properties of knowledge underlie the...