This article claims that the territorial structure of government results from a tension between scale and community. The benefits of scale arise from the nature of public goods, and include economic exchange, political power and protection against external shocks. Communities are double-edged in that they are characterized by parochial altruism. Altruism and social solidarity facilitate government within communities, but parochial attachments constrain government among communities. Scale and community, as theorized here, provide a setting for strategic choice. Both are in flux as patterns of human interaction change, and government itself shapes those patterns. Evidence is drawn from the five largest polities in the history of western Europe: the Roman Empire, the Frankish Empire, Napoleonic France, the Third Reich and the European Union.