1. Sectionalismwas the major cause of the United States Civil War because it was integral to creating the Southern social life as well as shaping its political tendencies, not the issue of slavery, which only affected a very small percent of southerners.
2. In the United States. Sectionalism in 1800s America refers to the different lifestyles, social structures, customs, and the political values of the North and the South. ... Historians have debated whether economic differences between the industrial Northeast and the agricultural South helped cause the Civil War.