This book provides a comprehensive, up-to-date, and expert synthesis of location theory. What are the impacts of a firm's geographic location on the locations of customers, suppliers, and competitors in a market economy? How, when, and why does this result in the clustering of firms in space? When and how is society made better or worse off as a result? This book uses dozens of locational models to address aspects of these three questions. Classical location problems considered include Greenhut-Manne, Hitchcock-Koopmans, and Weber-Launhardt. The book reinterprets competitive location theory, focusing on the linkages between Walrasian price equilibrium and the localization of firms. It also demonstrates that competitive location theory offers diverse ideas about the nature of market equilibrium in geographic space and its implications for a broad range of public policies, including free trade, industrial policy, regional development, and investment in infrastructure. With an extensive bibliography and fresh, interdisciplinary approach, the book will be an invaluable reference for academics and researchers with an interest in regional science, economic geography, and urban planning, as well as policy advisors, urban planners, and consultants.