The development of American federalism is a story of contested sovereignty, and those contests are fundamentally shaped by the evolving structures, relationships, and understandings of the constitutional order. This dissertation seeks to show how the American federal system is both cause and effect of political development. Even as it structures legal and political contestation, American federalism is shaped—even redefined—by such contestation. Central to the account of American federalism that I advance are two related arguments about the nature of the federal system. The first is that the Constitution’s definition of the state-federal relationship is structurally underdeterminate: while the Constitution constrains the set of permissible s...