This paper discusses the prevalence of Silicon Valley-style localizations of individual manufacturing industries in the United States. Several models in which firms choose locations by throwing darts at a map are used to test whether the degree of localization is greater than would be expected...

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...