This book offers an analytical explanation for the origins of and change in property institutions on the American frontier during the nineteenth century. Its scope is interdisciplinary, integrating insights from political science, economics, law and history. This book shows how claim clubs - informal governments established by squatters in each of the major frontier sectors of agriculture, mining, logging and ranching - substituted for the state as a source of private property institutions and how they changed the course of who received a legal title, and for what price, throughout the nineteenth century. Unlike existing analytical studies of the frontier that emphasize one or two sectors, this book considers all major sectors, as well as the relationship between informal and formal property institutions, while also proposing a novel theory of emergence and change in property institutions that provides a framework to interpret the complicated history of land laws in the United States.