Manifest Destiny

Manifest Destiny was the 19th century American belief that the United States (often, as Horsman (1981) notes, in the ethnically specific form of the "Anglo-Saxon race") was destined to expand across the North American continent, from the Atlantic Seaboard to the Pacific Ocean. It was used by Democrats in the 1840s to justify the war with Mexico; the concept was denounced by Whigs, and fell into disuse after the mid-19th century.

Advocates of Manifest Destiny believed that expansion was not only wise but that it was readily apparent (manifest) and inexorable (destiny).

The concept of American expansion is much older, but John L. O'Sullivan coined the exact term "Manifest Destiny" in the July/August 1845 issue of the United States Magazine and Democratic Review in an article titled "Annexation." It was primarily used by Democrats to support the expansion plans of the Polk Administration, but the idea of expansion faced opposition from Whigs like Henry Clay, Daniel Webster, and Abraham Lincoln who wanted to deepen the economy rather than broaden its expanse. John C. Calhoun was a notable Democrat who generally opposed his party on the issue, which fell out of favor by 1860.

The belief in an American mission to promote and defend democracy throughout the world, as expounded by Abraham Lincoln and Woodrow Wilson, continues to have an influence on American political ideology.