For centuries, the study of geography was about territorial discovery and mapping. In recent decades, it has become a more diffuse discipline, concerned with the complicated interactions between human societies and natural environments -- and it has dwindled as a teaching field in American academia. De Blij warns that Americans neglect geographic knowledge at their own peril. It is not geography's technical insights so much as its more general body of knowledge about territorial space, distance, and mental maps that make it so vital. For de Blij, geographic literacy is an essential element of America's global political literacy -- and its national security. The book makes this point in descriptive surveys of various facets of the world system: population, climate change, European integration, terrorism, post-Soviet Russia, and the meshing of civilizations. In the end, de Blij is surely right that American awareness of the geographic complexities of the world would help it navigate, but he never really offers a penetrating theory or an organizing idea about how and why geography matters, or explains what the academic field of geography has to offer in making sense of these long-term shifts.