Irish immigrants often crowded into subdivided homes that were intended for single families, living in tiny, cramped spaces. Cellars, attics and make-do spaces in alleys became home. Not only were many immigrants unable to afford better housing, but the mud huts in which many had lived in Ireland had lowered their expectations.

A lack of adequate sewage and running water in these places made cleanliness next to impossible. Disease of all kinds (including cholera, typhus, tuberculosis, and mental illness) resulted from these miserable living conditions. Thus, when the Irish families moved into neighborhoods, other families often moved out fearing the real or imagined dangers of disease, fire hazards, unsanitary conditions and the social problems of violence, alcoholism and crime.