Control of infectious agents also provided the impetus for immigrant medical inspections along the U.S. coasts in the late 19th century, but, in practice, it was the weeding out of chronic disease and disability that actually motivated public health officers on the line at Ellis Island and other U.S. immigration ...

The primary reason for the medical inspections at Ellis Island was to protect the domestic population of the United States from "loathsome or dangerous contagious diseases" such as tuberculosis, trachoma (a contagious eye infection), and favus (a scalp fungus). During the height of immigration between 1892 and 1954, the U.S. government operated under a strict policy of excluding anyone deemed "likely to become a public charge." This included not only the physically ill but also those with "mental deficiencies" or physical disabilities that might prevent them from working and supporting themselves. The "six-second physical" was a high-pressure screening process where doctors watched immigrants walk up stairs to check for breathlessness or limping and used buttonhooks to pull back eyelids to search for signs of infection. If a person was found to be diseased or disabled, they could be detained in the island's hospital or, in about 2% of cases, forcibly deported back to their country of origin at the expense of the steamship company that brought them.