For thousands of years, the Chinese and many other nations around the workd built defensive walls around their cities. This phenomenon is not well understood from an economic perspective. To rationalize the existence of city walls, we propose a simple model that relates the deimesions of city...

Rural-urban migrants in China appear to prefer nearby destination cities. To gain a better understanding of this phenomenon, we build a simple model in which migrants from rural areas choose among potential destination cities to maximize utility. The distance between a migrant's home village and...

China has long aimed to restrict population growth in large cities but encourages growth in small and medium-sized cities. At the same time, various government policies favor large cities. We conjecture that larger cities in China have more urban amenities and a better quality of life. We thus...