Explaining Sprawl with an Agent-Based Model of Exurban Land and Housing Markets

This paper develops a model of land use in a growing community on the urban fringe and uses it to explore the spatial patterns and time path of development. The model is an agent-based model (ABM) of housing and land markets that includes as agents farmer/landowners, a developer who buys land and builds houses, and consumers who purchase housing. Housing is characterized by lot size and house size. As in all ABMs, macro-scale patterns emerge from many micro-scale interactions between individual agents, which are modeled computationally. In contrast to many other ABMs, however, the fundamentals of microeconomic decisionmaking are built into the model — consumers choose houses to maximize utility; farmers compare returns from agriculture to the expected value of their land in development; and developers purchase land and build houses so as to maximize profits. Model simulations reveal some aspects of sprawl such as “leapfrog” development, yet also confirm some results from traditional urban economic models, such as declining density and rent (land price) gradients. Sensitivity analyses on the utility function parameters, the distribution of agricultural productivity, and the travel costs highlight the importance of the economic features of the model