This paper is concerced with the role of externalities and nonconvexities in agglomeration (concentration) of urban population and production. The paper examines whether, indeed, as often asserted, the external aspect of scale economies (diseconomies) deters (enhances) agglomeration.

It is common to explain the market failure in efficiently distributing the population among urban areas by externalities associated with unpriced transportation congestion and external scale economies in the supply of private and public goods. Consequently, in prescribing the appropriate...