Society was changing from rural (Country) to urban (City).
Explanation:
When the industrialization process started int he United States, the country started to change rapidly. Initially this process was not accepted the same everywhere, with the North embracing it while the South not being so fond of it but over time it took over all of the states.
The majority of the people lived in rural societies before the industrialization but once it started there was a massive shift of the population from the rural to the urban areas. This resulted in emptying of the rural areas and rapid increase in population and size of the cities. This happened first in the North, so huge cities rose like New York, Washington, Philadelphia, Chicago, Boston etc.
The South was slower in this process because it thought that the agriculture does the job for it economically. That quickly changed though with the change of policy of the country, so once the economic troubles started there was sharp demographic switch from the rural to the urban areas in this part of the United States.
