The Farm, the City, and the Emergence of Social Security
研究1880-1950年间美国社会保障制度的起源，通过一个包含农业和工业两部门的模型，分析人口迁移、生产率差异和投票机制如何推动社会保障从无到有。
During the period from 1880 to 1950 publicly managed retirement security \nprograms became an important part of the social fabric in most advanced \neconomies. In this paper we study the social, demographic and economic \norigins of social security. We describe a model economy in which \ndemographics, technology, and social security are linked together. We study \nan economy with two locations (sectors), the farm (agricultural) and the city \n(industrial). The decision to migrate from rural to urban locations is \nendogenous and linked to productivity differences between the two locations \nand survival probabilities. Furthermore, the level of social security is \ndetermined by majority voting. We show that a calibrated version of this \neconomy is consistent with the historical transformation in the United States. \nInitially a majority of voters live on the farm and do not want to implement \nsocial security. Once a majority of the voters move to the city, the median \nvoter prefers a positive social security tax, and social security emerges.