A 1917 US Public Health Service report described Ellis Island's medical inspection line in exact physical terms. Immigrants entered four lanes separated by iron railings; after fifteen feet, paired lanes merged into two. Doctors watched movement and appearance to identify people requiring further examination.
The National Park Service notes that the “line inspection” could give a doctor only about six seconds per person. The queue was therefore not merely crowd control. It was an observation device: applicants advanced while their movement itself became evidence. The building joined human flow and medical selection in one procedure.