Cities can be thought of as the absence of physical space between people and firms. As such, they exist to eliminate transportation costs for goods, people and ideas and transportation technologies dictate urban form. In the 21st century, the dominant form of city living is based on the automobile and this form is sometimes called sprawl. In this essay, we document that sprawl is ubiquitous and that it is continuing to expand. Using a variety of evidence, we argue that sprawl is not the result of explicit government policies or bad urban planning, but rather the inexorable product of car-based living. Sprawl has been associated with significant improvements in quality of living, and the environmental impacts of sprawl have been offset by technological change. Finally, we suggest that the primary social problem associated with sprawl is the fact that some people are left behind because they do not earn enough to afford the cars that this form of living requires.