Manifest Destiny: The belief held by many Americans in the mid-1800s that it was their destiny to expand westward across North America.
Second Great Awakening: A religious revival movement in the early 19th century that emphasized personal salvation and individual responsibility for moral behavior.
Transcontinental Railroad: A railway system built from coast to coast in the late 19th century that connected the eastern and western parts of the United States, facilitating trade and migration.