Manifest Destiny: Manifest Destiny was the belief popular in the 19th century that it was America's destiny and duty to expand its territory from coast to coast.
Treaty of Paris (1898): The Treaty of Paris (1898) ended the Spanish-American War and resulted in Spain ceding Puerto Rico, Guam, and Philippines to the United States.
Imperialism: Imperialism is when a country extends its power and influence through diplomacy or military force over other countries or territories for economic or strategic reasons.