* Overcrowding: As the population of cities increased, so did the demand for housing. This led to the construction of crowded, unsanitary slums.
* Pollution: The rapid industrialization of cities led to increased air and water pollution. This caused a number of health problems, including respiratory problems and waterborne diseases.
* Crime: The overcrowding and poverty of cities led to an increase in crime. This made it dangerous to live in many cities.
* Social problems: The rapid growth of cities also led to a number of social problems, including poverty, unemployment, and discrimination.
These problems eventually led to the decline of many cities in the United States.