ABSTRACT Every nation, formally or informally, defines and establishes the lines of political and fiscal authority among its national, regional, and local governments. Historically, centralized governments tend to restrict the power and autonomy of provincial and local governments. In this paper, we exploit the quasi-experimental distribution of political institutions in the Americas caused by variation in European colonial experience to examine the impact of institutions on urban and local development, specifically on the degree of urban primacy, the size distribution of cities, the number and density of local government units, and the fragmentation of metropolitan areas. We argue that centralization of political power at the national level, as experienced in many countries in Latin America, contributes to urban primacy and a size distribution of cities favoring large cities. Additionally, even in more politically decentralized countries such as Canada and the U.S., variance in political centralization at the provincial (state) level over local governments led to significant divergences in urban primacy, the distribution of city sizes, as well as the form, number, and density of local governments. While we cannot rule out the importance of other factors, our findings suggest that political centralization affects spatial economic development.