Most scholars agree the rise of states led to modern territoriality. Yet globally the transition to precise boundaries occurred most often in colonies, and there are virtually no systematic explanations of its occurrence outside Europe. This article explains how precise boundaries emerged in the earliest context where they were regularly and generally implemented: seventeenth- and eighteenth-century colonial North America. Unlike explanations of modern territoriality in Europe, it argues property boundary surveys became an entrenched practice on the part of settlers and were a readily available response to intercolonial boundary disputes. After independence, settlers who were accustomed to surveys pursued linear boundaries with Britain, Spain, and Russia. Moreover, the article argues that linear borders (delimited linearly and typically physically demarcated), not sovereignty, are constitutive of modern territoriality. By disentangling the literature’s Eurocentric confusion between modern territoriality and sovereign statehood, the article makes possible a global comparative study of the emergence of modern territoriality.