Manifest destiny was the expansionist colonial belief in the 19th-century United States that American settlers were destined to expand westward across North America, and that this belief was both obvious ("manifest") and certain ("destiny"). The belief is rooted in American exceptionalism, romantic nationalism, Anglo-Saxonism, and nascent ideas of white chauvinism, implying the inevitable spread of republicanism and the American way. It is one of the earliest expressions of American imperialism. According to historian William Earl Weeks, there were three basic tenets behind the concept: The assumption of the unique moral virtue of the United States, the assertion of its mission to redeem the world by the spread of republican government and more generally the "American way of life", and the faith in the nation's divinely ordained destiny to succeed in this mission.
Manifest destiny remained heavily divisive in politics, causing constant conflict with regard to slavery in these new states and territories. It is also associated with the expansion of European settlers onto the territories of Indigenous Americans and the annexation of lands to the west of the United States borders at the time on the continent. The concept became one of several major campaign issues during the 1844 presidential election, where the Democratic Party won and the phrase "Manifest Destiny" was coined within a year.
The concept of manifest destiny was used by Democrats to justify the 1846 Oregon boundary dispute and the 1845 annexation of Texas as a slave state, culminating in the 1846 Mexican–American War. In contrast, the large majority of Whigs and prominent Republicans (such as Abraham Lincoln and Ulysses S. Grant) rejected the concept and campaigned against these actions. By 1843, former U.S. president John Quincy Adams, originally a major supporter of the concept underlying manifest destiny, had changed his mind and repudiated expansionism because it meant the expansion of slavery in Texas. Ulysses S. Grant served in and condemned the Mexican–American War, declaring it "one of the most unjust ever waged by a stronger against a weaker nation".
After the American Civil War, the U.S. acquired Alaska in 1867. In the 1890s, Republican president William McKinley annexed Hawaii, the Philippines, Puerto Rico, Guam, and American Samoa. The 1898 Spanish–American War was controversial, and imperialism became a major issue in the 1900 United States presidential election. Historian Daniel Walker Howe summarizes that "American imperialism did not represent an American consensus; it provoked bitter dissent within the national polity".
There was never a set of principles defining manifest destiny; it was always a general idea rather than a specific policy made with a motto. Ill-defined but keenly felt, manifest destiny was an expression of conviction in the morality and value of expansionism that complemented other popular ideas of the era, including American exceptionalism and Romantic nationalism. Andrew Jackson, who spoke of "extending the area of freedom", typified the conflation of America's potential greatness, the nation's budding sense of Romantic self-identity, and its expansion.
Yet Jackson was not the only president to elaborate on the principles underlying manifest destiny. Owing in part to the lack of a definitive narrative outlining its rationale, proponents offered divergent or seemingly conflicting viewpoints. While many writers focused primarily upon American expansionism, be it into Mexico or across the Pacific, others saw the term as a call to example. Without an agreed-upon interpretation, much less an elaborated political philosophy, these conflicting views of America's destiny were never resolved. This variety of possible meanings was summed up by Ernest Lee Tuveson: "A vast complex of ideas, policies, and actions is comprehended under the phrase 'Manifest Destiny'. They are not, as we should expect, all compatible, nor do they come from any one source."
Most historians credit the conservative newspaper editor and future propagandist for the Confederacy, John O'Sullivan, with coining the term manifest destiny in 1845. However, other historians suggest the unsigned editorial titled "Annexation" in which it first appeared was written by journalist and annexation advocate Jane Cazneau.
O'Sullivan was an influential advocate for Jacksonian democracy, described by Julian Hawthorne as "always full of grand and world-embracing schemes". O'Sullivan wrote an article in 1839 that, while not using the term "manifest destiny", did predict a "divine destiny" for the United States based upon values such as equality, rights of conscience, and personal enfranchisement "to establish on earth the moral dignity and salvation of man". This destiny was not explicitly territorial, but O'Sullivan predicted that the United States would be one of a "Union of many Republics" sharing those values.
Six years later, in 1845, O'Sullivan wrote another essay titled "Annexation" in the Democratic Review, in which he first used the phrase manifest destiny. In this article, he urged the U.S. to annex the Republic of Texas, not only because Texas desired this, but because it was "our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions". Overcoming Whig opposition, Democrats annexed Texas in 1845. O'Sullivan's first usage of the phrase "manifest destiny" attracted little attention.
O'Sullivan's second use of the phrase became extremely influential. On December 27, 1845, in his newspaper the New York Morning News, O'Sullivan addressed the ongoing boundary dispute with Britain. O'Sullivan argued that the United States had the right to claim "the whole of Oregon":
And that claim is by the right of our manifest destiny to overspread and to possess the whole of the continent which Providence has given us for the development of the great experiment of liberty and federated self-government entrusted to us.
That is, O'Sullivan believed that Providence had given the United States a mission to spread republican democracy ("the great experiment of liberty"). Because the British government would not spread democracy, thought O'Sullivan, British claims to the territory should be overruled. O'Sullivan believed that manifest destiny was a moral ideal (a "higher law") that superseded other considerations.
O'Sullivan's original conception of manifest destiny was not a call for territorial expansion by force. He believed that the expansion of the United States would happen without the direction of the U.S. government or the involvement of the military. After Americans immigrated to new regions, they would set up new democratic governments, and then seek admission to the United States, as Texas had done. In 1845, O'Sullivan predicted that California would follow this pattern next, and that even Canada would eventually request annexation as well. He was critical of the Mexican–American War in 1846, although he came to believe that the outcome would be beneficial to both countries.
Ironically, O'Sullivan's term became popular only after it was criticized by Whig opponents of the Polk administration. Whigs denounced manifest destiny, arguing, "that the designers and supporters of schemes of conquest, to be carried on by this government, are engaged in treason to our Constitution and Declaration of Rights, giving aid and comfort to the enemies of republicanism, in that they are advocating and preaching the doctrine of the right of conquest". On January 3, 1846, in a speech Representative Robert Winthrop used the term for the first time in Congress stating:There is one element in our title [to Oregon], however, which I confess that I have not named, and to which I may not have done entire justice. I mean that new revelation of right which has been designated as the right of our manifest destiny to spread over this whole continent. It has been openly avowed in a leading Administration journal that this, after all, is our best and strongest title-one so clear, so pre-eminent, and so indisputable, that if Great Britain had all our other titles in addition to her own, they would weigh nothing against it. The right of our manifest destiny! There is a right for a new chapter in the law of nations; or rather, in the special laws of our own country; for I suppose the right of a manifest destiny to spread will not be admitted to exist in any nation except the universal Yankee nation!" Winthrop was the first in a long line of critics who suggested that advocates of manifest destiny were citing "Divine Providence" for justification of actions that were motivated by chauvinism and self-interest. Despite this criticism, expansionists embraced the phrase, which caught on so quickly that its origin was soon forgotten.