Many of the city's inhabitants, including scientists, thought that impoverished slum-dwelling immigrants were to blame even though the prevalence of the disease was higher in the more prosperous districts such as Staten Island – a pattern that had also been seen in cities like Philadelphia.
Suur osa linnaelanikest, sealhulgas teadlased, arvasid, et süüdi on slummides elavad vaesed sisserännanud, kuigi haigus levis pigem jõukamates linnaosades, nagu Staten Islandil (selline muster oli iseloomulik ka Philadelphia linnale).