Manifest Destiny: Manifest Destiny was a belief prevalent during the mid-19th century that it was America's destiny to expand its territory across North America from coast to coast.
Second Great Awakening: The Second Great Awakening was a religious revival movement during the early 19th century that emphasized personal salvation and social reform.
Monroe Doctrine: The Monroe Doctrine was a U.S. policy articulated by President James Monroe in 1823 warning European powers against further colonization or intervention in the Americas.