Manifest destiny

In the 19th century, Manifest Destiny was the widely held belief in the United States that American settlers were destined to expand throughout the continent. Historians have for the most part agreed that there are three basic themes to Manifest Destiny:

Historian Frederick Merk says this concept was born out of "A sense of mission to redeem the Old World by high example...generated by the potentialities of a new earth for building a new heaven".

Historians have emphasized that "Manifest Destiny" was a contested concept—Democrats endorsed the idea but many prominent Americans (such as Abraham Lincoln, Ulysses S. Grant, and most Whigs) rejected it. Historian Daniel Walker Howe writes, "American imperialism did not represent an American consensus; it provoked bitter dissent within the national polity.... Whigs saw America's moral mission as one of democratic example rather than one of conquest."

Newspaper editor John O'Sullivan coined the term Manifest Destiny in 1845 to describe the essence of this mindset which was a rhetorical tone. It was used by Democrats in the 1840s to justify the war with Mexico and it was also used to divide half of Oregon with Great Britain. But Manifest Destiny always limped along because of its internal limitations and the issue of slavery, says Merk. It never became a national priority. By 1843 John Quincy Adams, originally a major supporter, had changed his mind and repudiated Manifest Destiny because it meant the expansion of slavery in Texas.

Merk concludes:

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