Answer:
Sectionalism is the loyalty that someone give to his or her region, state or location of the country. This importance is above the country, sectionalism is to give more importance to the local above the Nation.
In the U.S., sectionalism increased from 1800 to 1850, because the North industrialised, building prosperous factories. On the other hand, the South concentrated in agriculture activities. The main difference was that slavery, the south defended slavery and criticised the ''white slaves in the North'', because Southern people said that in the North, employees were mistreated and not payed.