Manifest Destiny

In 1845, newspaper editor John O’Sullivan coined the term “Manifest Destiny” to describe the ideology of continental expansionism.

Though the term was new, the ideas underlying it were much older, dating back to the first colonial contact between Europeans and Native Americans. The ideology that became known as Manifest Destiny included a belief in the inherent superiority of white Americans, as well as the conviction that they were destined by God to conquer the territories of North America, from sea to shining sea.

The ideology of Manifest Destiny justified extreme measures to clear the native population from the land, including forced removal and violent extermination. For proponents of Manifest Destiny, the American Indians were mere impediments to the forward march of racial and technological progress, and they advocated pursuing a policy of Indian Removal.${}^1$‍

US President James Polk, who served one term in office, from 1845 to 1849, is the leader most associated with the ideology of Manifest Destiny. Polk was a Democrat from Tennessee who had served as Speaker of the House of Representatives and Governor of Tennessee before becoming president. As president, he led the United States to victory over Mexico in the Mexican-American War, which culminated in the transfer of a vast new territory, comprising almost the whole of the modern-day Southwest, from Mexico to the United States.${}^2$‍

Polk also resolved the boundary dispute with Great Britain over the Oregon Territory, which had been jointly occupied since 1818. Polk's administration negotiated the Oregon Treaty of 1846 with Britain, which accepted a division of the territory between the United States and Canada at the 49th parallel. The territory acquired by the United States under the provisions of the treaty include the present-day states of Idaho, Oregon, and Washington, as well as parts of Montana and Wyoming.

Polk's embrace of Manifest Destiny and the acquisition of new territories inflamed tensions between abolitionists and slaveholders and heightened conflict between white settlers and Native Americans.${}^3$‍ While the North and South fought over whether the new states admitted to the Union were to be free states or slave states, the battles between the Plains Indians and settlers in Texas grew particularly vicious. Though Comanches put up an especially fierce resistance to the encroachment of white people onto their lands, they were ultimately vanquished and relocated to a reservation in Oklahoma in 1875.

Meanwhile, the debate over the Wilmot Proviso was one of the major events leading up to the Civil War. The proviso, which was strongly opposed by the slaveholding South, asserted that the Mexican-American War had not been fought for the purpose of expanding slavery, and stipulated that slavery would never exist in the territories acquired from Mexico in the war. Ultimately, Polk’s territorial expansionism, though aimed at national unity, wound up intensifying sectional conflict and further paving the road to civil war.${}^4$‍

Why do you think Polk went to war with Mexico but negotiated with Great Britain?

In your view, what was the most significant component of the ideology of Manifest Destiny?

What sorts of policies were justified in the name of Manifest Destiny?

What were the most consequential outcomes of the ideology of Manifest Destiny?