The Second World War's global dimensions necessitated an intellectual mobilization dedicated to the study of the world's geographical regions. In the United States, the production of this intelligence prepared the ground for Cold War area studies, as information on certain cultural and natural spaces was collected and classified in central repositories or published in comprehensive manuals. Using archival and period sources, this article employs the central example of the Smithsonian Institution's Ethnogeographic Board to trace the relationship between the production of geographical knowledge and American military practices during the war. Through survival guides, services to intelligence agencies, filing efforts, and surveys of areal education, the board crafted a cartographic framework with a specific structure. The regional parts of this map were environments where the reach of militarism and social science could be localized. This study contributes to an understanding of geography's crucial relationship with militarism, and to the related history of geographical thought and practice during the Second World War by considering applied intellectual work and by transgressing disciplinary boundariesboundaries that were of little importance in wartime-to demonstrate that both regional and systematic approaches to geography could be made flexible in the face of geopolitical demands.