The correct answer to this open question is the following.
One specific problem that was caused by the rapid growth of cities during the period from 1865 to 1900 was overpopulation. Yes, overcrowded spaces because many people, including immigrants who arrived in the largest cities of the United States such as New York or Chicago, because there were many industries that were offering jobs to operate the machines in the factories.
The problem of overcrowded spaces was a real issue that caused many conflicts in those above-mentioned years. People lived in small rooms with unhealthy conditions. There was not enough ventilation and diseases spread quickly. There were not enough public services that could satisfy the necessities of that large number of people.
