Initiated in the late 1910s at the urging of federal and state officials determined to protect the young soldiers massing for World War I from the “scourges” of prostitution and venereal disease, the American Plan was part of a broader crusade known as the “social hygiene” movement, which sought to wield public health techniques to address the social causes of syphilis and sex work. Many social hygienists (such as the prominent New York physician Prince A. Morrow) believed that venereal disease and promiscuity were, in effect, a matter of heredity. While merely “silly” or “untrained” women could be reformed, the thinking went, a significant proportion of sex workers were congenitally “feebleminded,” in the language of the time. “Virtually half of the country’s prostitutes are mentally deficient,” the military psychologist Paul A. Mertz wrote in the Journal of the American Medical Association in 1919. Feeblemindedness in women, in turn, was thought to manifest in prostitution or other forms of deviancy.
This sort of thinking grew out of eugenics, which held that some people are genetically endowed with superior intelligence or ethics while others are cursed by poor genes with stupidity, indolence, or criminality. In the first half of the twentieth century, this was a popular social theory, and eugenicists (especially those in the US) maintained that the human race could be “improved” through selective breeding, accomplished by “positive” programs such as family planning and marriage counseling as well as “negative” programs such as institutionalization.
Many social hygienists were prominent promoters of the program of “eugenic” sterilization—most notably Paul Popenoe, author of the first major eugenics textbook, who, as a federal agent in the late 1910s, pushed officials in Texas, New Mexico, and Arizona to incarcerate as many women with STIs as they could, Black and Hispanic women above all. Across the country, administrators of the American Plan subjected incarcerated women to intelligence tests to determine feeblemindedness. A memorandum, sent in 1917 from the federal government to every state governor, demanded such testing, to be followed by “the commitment to institutions of non-diseased prostitutes for industrial training and for the commitment of all feeble-minded prostitutes to custodial care.”