"}\nAntebellum New Orleans sat at the heart of America\u2019s slave and cotton \nkingdoms. But it was also the nation\u2019s \u201cnecropolis,\u201d with yellow fever \nroutinely killing about 8 percent of its population. With little \nepidemiological understanding of mosquito-borne viruses\u2014and meager \npublic health infrastructure\u2014a person\u2019s only protection against the \nscourge was to \u201cget acclimated\u201d: fall sick with, and survive, yellow \nfever. About half of all people died in the acclimating process. \nRepeated epidemics generated a hierarchy of immunocapital whereby \n\u201cacclimated citizens\u201d (survivors) leveraged their immunity for social, \neconomic, and political power and \u201cunacclimated strangers\u201d (poor recent \nimmigrants) languished in social and professional purgatory. For whites,\n acclimation was the quintessential demonstration of calculated \nrisk-taking: that people had paid their biological dues, were worthy of \ninvestment, and could now justifiably pursue economic advancement in \nslave racial capitalism. For black slaves, who were embodied \ncapital, immunity enhanced the value and safety of that capital for \ntheir white owners, strengthening the set of racialized assumptions \nabout the black body bolstering racial slavery. By fusing health with \ncapitalism, this article presents a new model\u2014beyond the toxic fusion of\n white supremacy with the flows of global capitalism\u2014for how power \noperated in nineteenth-century Atlantic society.\n\n