Puerto Rico has been a territorial possession of the United States for over one hundred years. As a strategic insular possession and guardian of the Panama Canal, a lucrative offshore investment site for U.S. multinational corporations, and a long-standing source of labor power, Puerto Rico has had an important role in American history since 1898.This book provides a new and comprehensive interpretation of how the United States attempted to transform Puerto Rico from a neglected backwater of the Spanish empire into one of its key props in establishing hegemony in the western hemisphere. The book looks at the formative three-and-one-half decades of U.S. colonial rule, when the colony's key institutions, economic structures, and legal doctrines were transformed. Policy papers, speeches, newspaper articles, and memoirs from the period inform the study with particular detail and insight. The book also looks at the dynamics of U.S. expansionism during the Progressive Era and examines the normative and ideological constructions that were used to rationalize a campaign of territorial acquisition and colonial administration. It also demonstrates how the military and subsequent civilian regimes directed a process of institutional transformation, state building, and capitalist development.