This chapter brings together key strands of transport geography and economic geography, two fields which have become separated from one another in recent decades, in spite of the manifold connections between them on the ground. It also informed by relevant insights from development studies. In contrast to the economic geography and transport geography literatures respectively, it takes neither mobility nor the existing spatial distribution of economic activity for granted, assessing the dynamic linkages between the two. The authors view the relationship between transport and economic development as a two-way symbiosis; in a circular manner, each influences the other. The primary concern is with the secondary or additional effects of transport investment in altering economic conditions rather than its direct impact in terms of reduced travel times and increased accessibility. The next section of the chapter revisits some major theoretical frameworks that have been used to interpret and understand the nexus between transport and economic development. The authors then discuss the relationship between transport and spatial development in developed countries, considering the role of transport in the shift to post-Fordist production systems and assessing the economic effects of investments in transport infrastructure. A discussion of transport and economic development in developing countries precedes the brief conclusion, which summarizes the main points of the chapter.