Economic Integration and Political Disintegration
建立模型分析贸易开放度如何影响国家的最优规模和数量，并检验了两个推论：贸易开放度调节了国家规模的经济收益，且贸易体制影响了民族国家的创建与分裂历史。
In a world of trade restrictions, large countries enjoy economic benefits, because political boundaries determine the size of the market. Under free trade and global markets even relatively small cultural, linguistic or ethnic groups can benefit from forming small, homogeneous political jurisdictions. This paper provides a formal model of the relationship between openness and the equilibrium number and size of countries, and successfully tests two implications of the model. Firstly, the economic benefits of country size are mediated by the degree of openness to trade. Secondly, the history of nation-state creations and secessions is influenced by the trade regime.