Alfred Marshall argues that industrial agglomerations exist in part because individuals can" learn skills from each other when they live and work in close proximity to one another. An" increasing amount of evidence suggests that the informational role of cities is a primary reason for" their continued existence. This paper formalizes Marshall's theory in a model where individuals" acquire skills by interacting with one another, and dense urban areas increase the speed of" interactions. The model predicts that cities will have a higher mean and higher variance of skills." Cities will attract young people who are not too risk averse and who benefit most from learning" (e.g. more patient people). Older, more skilled workers will stay in cities only if they can" internalize some of the benefits that their presence creates for young people. The level of" urbanization will rise when the demand for skills rises, when the ability to learn by imitation rises or when the level of health in the economy rises. Empirical evidence on urban wages supports the" learning view of cities and a variety of other implications of the theory are corroborated" empirically.
