Final answer:
Manifest Destiny describes the belief that the U.S. was destined to occupy all of North America, spreading democratic values and establishing political and economic control. This expansionist viewpoint was a central element of the westward movement in the 1840s, leading to significant territorial acquisitions.
Step-by-step explanation:
The term Manifest Destiny best describes the belief that the U.S. was divinely willed to occupy all of North America. This concept emerged in the 1840s and suggested that American expansion was inevitable, just, and predetermined by divine will. It encompassed the idea that Americans were destined to spread democratic institutions and political and economic control 'from sea to shining sea,' Americanizing the inhabitants, such as Indians and Mexicans, in the process.
Manifest Destiny was a driving force for the westward expansion movement and justified the extension of U.S. territory, eventually leading to the annexation of Texas and Oregon, as well as the war with Mexico that resulted in the acquisition of territories such as California. The expansion was seen as a moral imperative and was often used to rationalize the displacement and mistreatment of indigenous peoples.