This book discusses the economics of transport infrastructure and the economic theorizing around transport infrastructure from 1850 to today. Transport infrastructure systems are continuously evolving over time. Since the mid-1800s these systems have grown in complexity and outreach. They have been important drivers of economic development but have also been important as economic agents in themselves. Over time transport infrastructure systems have taken on different functions as providers of simpler transport services or more developed value chain components. Transport infrastructure has also been a source for different arguments about economic theory and practice.  Transport infrastructure systems are analysed from an institutional perspective where the long-term development of the ownership and financing of the systems, as well as the connection to different policy areas are elaborated. A longitudinal study of Sweden transport infrastructurepolicy is used to exemplify driving factors causing change and transformation of the systems over time with different scale and scope.