The location of a government's capital can profoundly influence the nature and quality of political representation. Yet scholars know very little about what drives the siting of political capitals. In this article, we examine the location and relocation of political capitals in the United States, including the choice of Washington, DC, as the nation's capital and the location and relocation of capitals in the 48 contiguous American states. We argue that the location of capitals in the United States followed a systematic pattern in accord with the theory of representative government developed in the new nation, especially as articulated by Madison. Based on an empirical analysis of historical census and political boundaries data from 1790 to the present, we find that decision makers consistently tended to locate—and especially relocate—the seat of government as near as possible to the population centroid of the relevant political jurisdiction, consistent with the principle of equal representation of citizens. Our analysis contributes to the study of institutional design and change, especially in the area of American political development, as well as to a burgeoning literature on the effects of geographical factors on political outcomes.