Manifest Destiny: Manifest Destiny was the belief in the 19th century that it was America's destiny to expand its territory from coast to coast.
Reconstruction: Reconstruction refers to the period after the Civil War when efforts were made to rebuild and restore the Southern states and address issues such as slavery and civil rights.
Cold War: The Cold War was a period of political tension and military rivalry between the United States and Soviet Union, marked by ideological conflict, arms race, and proxy wars.