This article examines the effect of cartography on the development of the modern state system. I argue that new mapping technologies in early modern Europe changed how actors thought about political space, organization, and authority, thus shaping the creation of sovereign states and international relations. In particular, mapping was fundamental to three key characteristics of the medieval-to-modern shift: the homogenization of territorial authority, the linearization of political boundaries, and the elimination of nonterritorial forms of organization. Although maps have been interpreted as epiphenomenal to political change, each of these three transformations occurred first in the representational space of maps and only subsequently in the political practices of rulers and states. Based on evidence from the history of cartographic technologies and their use by political actors, the practices and texts of international negotiations, and the practical implementation of linearly bounded territoriality by states, this article argues that changes in the representational practices of mapmaking were constitutive of the early-modern transformation of the authoritative structure of politics. This explanation of the international system's historical transformation suggests useful new directions for investigations into the possibility of fundamental political change due to the economic, social, and technological developments of globalization.