Communication externalities in cities

To identify communication externalities in French cities, we exploit a unique survey recording workplace communication of individual workers. Our hypothesis is that in larger and/or more educated cities, workers should communicate more. In turn, more communication should have a positive effect on wages. By estimating both an earnings and a communication equation, we find evidence of communication externalities. In larger and more educated cities, workers communicate more and in turn this has a positive effect on their wages. Depending on the estimates, we find that 13 to 22% of the effects of a more educated and larger city on wages percolate through this channel.