This paper summarizes economic research on investment in public infrastructure and introduces the findings of several new studies on this topic. It begins with a review of several potential justifications for the public sector's involvement in building, financing, and operating infrastructure,...

Cities are shaped by transportation infrastructure. Older cities were anchored by waterways. Nineteenth century cities followed the path of streetcars and subways. The 20th century city rebuilt itself around the car. The close connection between transportation and urban form is natural, since...

Cities generate negative, as well as positive, externalities; addressing those externalities requires both infrastructure and institutions. Providing clean water and removing refuse requires water and sewer pipes, but the urban poor are often unwilling to pay for the costs of that piping....