Sectionalism: Sectionalism refers to loyalty or support for one's own region (North or South) rather than the whole country. It often contributed to conflicts and tensions between the Northern and Southern states.
Popular sovereignty: Popular sovereignty was a principle that allowed residents of new territories to decide whether they would allow slavery within their borders or not. This issue further intensified North-South relations leading up to the Civil War.
Nullification Crisis: The Nullification Crisis was a conflict between South Carolina and the federal government over tariffs imposed on imported goods. It highlighted disagreements between Northern interests in protecting industry through tariffs and Southern interests in maintaining free trade.