Duopoly locations and optimal zoning in a small open city

This paper analyzes a duopoly location model with an asymmetric zoning that prohibits firms from locating to a specific interval in a small open linear city. It is shown that the maximum differentiation principle presented in d'Aspremont et al. Econometrica 47 (1979) 1145] is still valid under area zoning regulation. Moreover, a zoning regulation can be seen as a policy instrument to limit firms' excess profits, and a proper regulation may even reduce the distortion in total transportation costs, therefore enhancing social welfare. Specifically, the optimal zoning is about 29.5 percent of the city with no amenity effect. Finally, all the land rents raised by zoning are eventually confiscated by the absentee landowner.