Manifest Destiny: How America Justified Westward Expansion
During the first half of the 19th century, the United States population witnessed a near five-fold expansion due to high birth rates and a rising tide of immigration from Europe. Combined with the economic depressions of 1819 and 1839, westward migration exploded as Americans searched for new land and opportunities.
United States Purchases New Territories
In response, President Thomas Jefferson negotiated the Louisiana Purchase from France in 1803, which doubled the size of the United States, followed by the acquisition of Florida from Spain in 1819. By the time Texas gained statehood in December of 1845, the notion that the U.S. would inevitably expand to the Pacific Ocean had become so widely accepted in the mind of most Americans, setting in motion a flood of migration and political will into what would become the American west.
What is Manifest Destiny?
The term “Manifest Destiny” first appeared in an editorial published in the the Democratic Review in the summer of 1845, when a writer made criticism of the lingering opposition to the annexation of Texas from Mexico, urging readers toward a national unity for “the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.”
That same summer, an article by John O’Sullivan in the New York Morning News referenced “Manifest Destiny” in light of the Oregon Territory, which was another vast swath of land that American politicians and laymen alike were eager to assert control over. By the time the Oregon Territory joined the U.S. following a treaty with Great Britain, America was now embroiled in the Mexican-American War of 1846 to 1848, which was driven by the spirit of “Manifest Destiny,” as pioneers freely encroached upon Mexican land.
When war ended with the signing of the Treaty of Guadalupe Hidalgo, 525,000 square miles were added to the United States’s landing holdings, including what is now California, Arizona, Colorado, New Mexico, Nevada, Utah and Wyoming. While the conquering spirit of Manifest Destiny witnessed a near stunning territorial expansion over the first half of the 19th century, the unrelenting westward spread of Americans not only led to war with Mexico, but also witnessed the wanton mistreatment and dislocation of Hispanics, Native Americans and other non-Europeans living in the path of westward settlers, at the same time fueling a contentious two-sided debate over which new territories and states would embrace the brutal institution of slavery, eventually leading a divided nation headlong into Civil War.