Manifest destiny

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.