A Spatial Theory of Trade
用一个包含连续区域、运输成本和外部性导致集聚效应的贸易模型，分析不同运输成本和外部性参数下的均衡专业化和贸易模式，为边界效应和引力方程提供空间分布角度的解释。
The equilibrium relationship between trade and the spatial distribution of economic activity is fundamental to the analysis of national and regional trade patterns, as well as to the effect of trade frictions. We study this relationship using a trade model with a continuum of regions, transport costs, and agglomeration effects caused by production externalities. We analyze the equilibrium specialization and trade patterns for different levels of transport costs and externality parameters. Understanding trade via the distribution of economic activity in space naturally rationalizes the evidence on border effects and the “gravity equation.”