One or two cases of human plague occur on the average in the United States each year. The occurrence of seven cases in 1965 and five in 1966 led to this review of the available records. A total of 547 cases of human plague with 349 deaths was reported in the continental United States from 1900 to 1966. Epidemics, following epizootics in urban rats, account for 432 of the cases with 284 deaths, all prior to 1925. From 1908 to 1966, contact with wild-rodent sources caused an additional 115 cases with 65 deaths.
Caten JL, Kartman L. Human Plague in the United States 1900-1966. JAMA. 1968;205(6):333-336. doi:10.1001/jama.1968.03140320027008