Manifest Destiny: This term refers to the belief that it was America's destiny and duty to expand westward, which often involved debates over whether newly acquired territories would allow or prohibit slavery.
Popular Sovereignty: This term refers to the idea that residents of a territory should have the right to decide whether their territory allows or bans slavery through voting.
Sectionalism: This term describes strong loyalty and identity towards one's own region, often leading to conflicts between different regions over issues such as slavery.