What were the differences between the North's and South's economy before the Civil War that made Civil War inevitable?

Answer 1

The economy of the South was based primarily on cotton monoculture supported by slave labor. Their cotton was sold to Europe for hard currency (and some to northern factories as well.) Southern farmers, especially plantation owners growing cotton, were in favor of slavery AND low tariffs on imported goods.

The North's economy was far more diverse, having a mix of factories, agriculture primarily based on grains, shipbuilding, and transportation. Their manufacturing interests were protected from foreign competition by high tariffs on imported goods. This made the North against slavery, which they felt gave the South an advantage in agriculture costs, AND high tariffs, which protected the factories of North from cheap, and frankly better made products from Europe. This disparity made conflict inevitable and prompted crises in 1820, 1830, 1850 and finally secession in December of 1860.