How did modern territorial states come to replace earlier forms of organization, defined by a wide variety of territorial and non-territorial forms of authority? Answering this question can help to explain both where our international political system came from and where it might be going.

In this dissertation, I argue that the use of new mapping technologies in early modern Europe was a fundamental driver of these monumental political developments. New cartographic tools altered how political actors understood political space, authority, and organization, reducing the wide variety of medieval political forms down to the unique territorial form of the sovereign state. Mapping and its use was necessary--though not sufficient--to drive the complex process leading to our world of territorial states.

Using evidence from the history of cartography, peace treaties, and political practices, I argue that early modern mapping changed the fundamental framework of political interaction. Authority structures not depicted on maps were ignored or actively renounced in favor of those that were, leading to the implementation of linear boundaries between states and centralized territorial rule within them. These fundamental characteristics of modern statehood appeared first in the representational space of maps and only subsequently in political practices on the ground. My exploration of this relationship reveals that maps and their depictions were causal, not epiphenomenal, to the transformation of politics.

The role of cartography in the formation of modern states is made evident when depictions in maps are compared against actual boundary practices and the language of peace treaties. Clear linear divisions between territorial political units, while pervading maps since the sixteenth century, did not become common in practice until late in the eighteenth century. For their part, mapmakers never intended to reshape political ideas and structures. Rather, their choice to depict the world as composed of homogenous political territories was independent of politics. It was driven by the dual incentives of a commercial market for aesthetically pleasing printed maps and the underlying geometric structure of early-modern cartography that is provided by the globe-spanning grid of latitude and longitude. Thus, by linking developments in cartography to political ideas and outcomes, my dissertation yields an analysis of the complex relation between technological and political change that acknowledges the importance of both material and ideational factors to the constitution of political institutions such as the state and the international system. My historical case also yields implications for how we might better understand transformative political change, particularly in today's globalizing international system.