In the last half of the nineteenth century, yellow fever plagued the American South. It stalked the region's steaming cities, killing its victims with overwhelming hepatitis and hemorrhage. Margaret Humphreys explores the ways in which this tropical disease hampered commerce, frustrated the scientific community, and eventually galvanized local and federal authorities into forming public health boards. She pays particular attention to the various theories for containing the disease and the constant tension between state and federal officials over how public funds should be spent. Her research recovers the specific concerns of the late nineteenth- and early twentieth-century South, broadening our understanding of the evolution of preventive medicine in the United States.