Commuting, congestion, and employment dispersal in cities with mixed land use

摘要

For centuries, cities have been modeled as having centered employment―scarce access to which generates land rent. This paper first presents some new empirical evidence that in US cities actual employment turns out to be almost as dispersed as residences. This range of urban forms is generated with analytic ease in a model that assumes land can have "mixed" rather than exclusive use at any location. The model has firms trading off a central-agglomeration force against the lower wages that accompany shorter commuting distances in peripheral locations. At one extreme, with very high agglomerative forces, employment is approximately centered, with long commute distances and high congestion levels. At the other extreme, lower agglomerative forces lead to employment that is completely dispersed, commute distances of zero and the absence of congestion. Maximizing output-minus-congestion never leads to a pattern of land mixing where employment is fully dispersed. A market model, however, often does if the mix at each location is based on the relative magnitude of the land rent offered from residential as opposed to commercial uses.