The correct answer is the North was becoming more urban and industrial.
North and South were the opposite in 1820, especially on the economic side. The Northern state's economy was based on industrial growth and big cities, the Southern states were based on a rural economy. This was the main problem that led to the war because the industries in the North showed them that they did not need slaves to prosper, the South did not agree with it and wanted to keep the slavery system because of their huge cotton plantations.
