Manifest Destiny: Manifest Destiny was the belief that it was America's destiny to expand its territory from coast to coast, often by displacing or assimilating Native American tribes.
Industrial Revolution: The Industrial Revolution was a period of rapid industrialization characterized by the development of new manufacturing processes, machinery, and factories.
Sectionalism: Sectionalism refers to loyalty or support for one's own region over national unity. During Period 4, sectional tensions between the North and South grew due to differences in economic systems and attitudes towards slavery.