A comprehensive survey of the technology of mapping and its relationship to the battle against disease, this look at medical mapping advances a radical argument that maps are not merely representations of spatial realities but a way of thinking about relations between viral and bacterial communities, human hosts, and the environments in which diseases flourish. The history of medical mapping is traced—from its growth in the 19th century during an era of trade and immigration to its renaissance in the 1990s during a new era of globalization. Referencing maps older than John Snow's famous cholera maps of London in the mid-19th century, this survey pulls from the plague maps of the 1600s, while addressing current issues concerning the ability of GIS technology to track diseases worldwide.