Answer:
Tenements
Step-by-step explanation:
During the late 1800s, millions of people emigrated to the United States, especially from Europe, but also a few from Asia and Latin America. American born population also grew by high rates due to high fertility rates, and falling mortality rates.
This brought massive population growth to American cities, and to keep with this demand, large tenements were built.
In these tenements, dozens of families shared the same building, often in small apartments of low quality and low sanitation. Sometimes epidemics ran through, and social conflicts were also common.