The American expansionist movement did not begin with Manifest Destiny and the push westward in the 1840s. Americans had been pushing boundaries since the colonial era, most notably across the Appalachian Mountains and into the Ohio River Valley. President Thomas Jefferson set the stage for expansionism with the Louisiana Purchase in 1803 and the movement grew in the 1830s with President Andrew Jackson’s Indian Removal Act, which “freed” land east of the Mississippi for the expanding population. The Louisiana Purchase and the journey of Lewis and Clark’s Corps of Discovery captured the imagination of many Americans, who dedicated themselves to the economic exploitation of the western lands and the expansion of American influence and power. In the South, the Adams-Onís Treaty of 1819 legally secured Florida for the United States, though it did nothing to end the resistance of the Seminole tribe against American pioneers and settlers. At the same time, the treaty frustrated those Americans who considered Texas a part of the Louisiana Purchase.

Rapid Growth

At the turn of the century, the overwhelming majority of American citizens lived east of the Appalachian Mountains; just fifty years later, about half of all Americans lived west of the mountains, a tremendous demographic shift. The rapid western expansion of the 1840s was largely a result of demographic, economic, and political pressures on the east coast. The population of the United States grew rapidly in the period from 1800-1850, rocketing from about five million to over twenty million in a fifty-year period. Americans were increasingly land-hungry as populations in cities and towns grew. On many of the overworked farms of the East, soil fertility was declining, making the cheap land of the West more and more attractive. Politically, many feared that if the United States did not occupy the West, then the British would. Some reasoned that westward expansion would counterbalance the increasingly industrialized and urbanized northeast, assuring that the republic of the United States would continue to be rooted in the ideals and values of Jefferson’s yeoman farmer (non-slaveholding, small landowning, family farmers). After the War of 1812, Americans settled the Great Lakes region rapidly thanks in part to aggressive land sales by the federal government. Selling federal lands, mostly taken from Native Americans through treaties or conflict, was a major source of revenue for the government and officials were eager to survey and sell large parcels to new settlers.

Questions of Slavery

Missouri’s admission to the Union as a slave state in 1821 following the Missouri Compromise presented the first major crisis over westward migration and American expansion in the antebellum period. Under the Missouri Compromise, Missouri and Maine entered the Union at the same time, Maine as a free state, Missouri as a slave state, and a line was drawn across the remainder of the Louisiana Territory north of which slavery was forbidden. Farther north, lead and iron ore mining spurred development in Wisconsin. By the 1830s and 1840s, increasing numbers of German and Scandinavian immigrants joined easterners in settling the Upper Mississippi watershed. Little settlement occurred west of Missouri as migrants viewed the Great Plains as a barrier to farming, the Rocky Mountains as undesirable to all but fur traders, and local Native Americans as too powerful to allow White expansion.

Territorial ambitions deeply influenced U.S. foreign policy; to the South, tensions arose with Mexico as thousands of Americans immigrated into the Mexican state of Coahuila y Tejas, hereafter referred to as Texas. Expansion was also deeply economically motivated. For example, Eastern merchants wanted control of west coast ports to trade with Asia. Overall, many Americans envisioned the same end, even though they favored expansion for different reasons; many, however, came to equate the idea of “spreading freedom” with spreading the United States.

Manifest Destiny

Figure 1. Artistic propaganda like this promoted the national project of Manifest Destiny. Columbia, the female figure of America, leads Americans into the West and into the future by carrying the values of republicanism (as seen through her Roman-style toga) and progress (shown through the inclusion of technological innovations like the telegraph) and clearing Native peoples and animals, seen being pushed into the darkness. Also note how close the Atlantic and Pacific Oceans are depicted, indicating how the pioneers pictured their mission: to connect the two coasts with American ideals of Democracy and technology.

The concept of Manifest Destiny gave a religious and cultural justification to American expansion across the continental United States. Millions of Americans professed the belief that the destiny of the United States was fto spread democratic institutions and the ideals of Western civilization “from sea to shining sea.” Manifest Destiny asserted that Americans would expand to the limits of North America, taking political and economic control of the continent. In the process, the inhabitants of North America, including Native Americans and Native Mexicans, would be colonized and assimilated into Western culture. Any attempt to resist would be forcibly extinguished. Some Americans even argued that, in effect, God had chosen them to control the entire Western Hemisphere. These viewpoints are evident in the speech of Missouri Senator Thomas Hart Benton, one of the leading proponents of Manifest Destiny:

I know of no human event, past or present, which promised a greater, and more beneficent change upon the earth than the arrival of…the Caucasian race…It would seem that the white race alone received the divine command, to subdue and replenish the earth! for it is the only race that has obeyed it—the only one that hunts out new and distant lands, and even a New World, to subdue and replenish…the Caucasian race now top[s] the Rocky Mountains, and spread[s] down the shores of the Pacific. In a few years a great population will grow up there, luminous with the accumulated lights of the European and American civilization…The Red race has disappeared from the Atlantic coast: the tribes that resisted civilization met extinction… For my part, I cannot murmur at what seems to be the effect of divine law… Civilization, or extinction, has been the fate of all people who have found themselves in the track of advancing Whites, and civilization, always the preference of the Whites, has been pressed as an object, while extinction has followed as a consequence of its resistance.

The Expansion of Slavery

However, the issue of expansion was certainly not that simple. The idea and effects of Manifest Destiny raised challenging and hotly-debated questions that were taken up by both the American government and its people. Was expansionism morally justifiable? And moreover, could a government accept and even promote expansion through moral action, or were the two mutually exclusive? Would the nation fundamentally change with the incorporation of distant lands and new populations (perceived by many as “unable to assimilate” into the U.S. population)? Would unchecked expansionism threaten American military and economic security? Was the expansion of the United States synonymous with the expansion of freedom? Finally, how was the growing nation to expand without upsetting the precarious balance between free and slaveholding states?

In the first half of the nineteenth century, the Southwest Ordinance of 1790 mandated the Ohio River as a dividing line between slave states and free states, with states to the south of the river being open to slavery. Consequently, the states north of the river were largely characterized by family farms and free-market labor, and to the south, they were largely characterized by enslaved labor. As the expansionist movement grew in the 1840s, the nation struggled to maintain the de facto “stalemate” between slave and free states as territories were incorporated into the nation as new states.

By 1850, seven states (California, Illinois, Indiana, Iowa, Maine, Michigan, and Wisconsin) had entered the union as free states, and six as slave states (Alabama, Arkansas, Florida, Mississippi, Missouri, and Texas). As the concept of Manifest Destiny developed, it became increasingly apparent that it applied to White Americans only, not only because of the maintenance and spread of slavery as a part of westward expansion but also because of White Americans’ attitudes and policies towards the Native populations of areas such as Texas and California.

Manifest Destiny also became a justification for the aggressively expansionist policies of President James Polk (1845-1849), who oversaw the annexation of Texas, the acquisition of the Oregon Territory from Great Britain, and the Mexican Cession of much of the Southwestern U.S. after the Mexican-American War.

origins of ‘Manifest Destiny’

Figure 2. John O’Sullivan, shown here in a 1874 Harper’s Weekly sketch, coined the phrase “manifest destiny” in an 1845 newspaper article.

John Louis O’Sullivan, a popular editor and columnist, coined the famous term for the long-standing American belief in the God-given mission of the United States to lead the world in the peaceful transition to democracy. In a little-read essay printed in The United States Magazine and Democratic Review, O’Sullivan outlined the importance of annexing Texas to the United States:

Why, were other reasoning wanting, in favor of now elevating this question of the reception of Texas into the Union, out of the lower region of our past party dissensions, up to its proper level of a high and broad nationality, it surely is to be found, found abundantly, in the manner in which other nations have undertaken to intrude themselves into it, between us and the proper parties to the case, in a spirit of hostile interference against us, for the avowed object of thwarting our policy and hampering our power, limiting our greatness and checking the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.¹

O’Sullivan and many others viewed expansion as necessary to achieve America’s destiny and to protect American interests. The quasi-religious call to spread democracy coupled with the reality of thousands of settlers pressing westward due to urban overcrowding, manifest destiny was grounded in the belief that a democratic, agrarian republic would save the world.

The ‘Religion’ of American Democracy

Although coined in 1845, Manifest Destiny was a widely held but vaguely defined belief that dated back to the founding of the nation and comprised three main facets. First, many Americans believed that the strength of American values and institutions justified moral claims to hemispheric leadership. They also felt that the lands on the North American continent west of the Mississippi River (and later into the Caribbean) were destined for American-led political and agricultural improvement. Last, there was the notion that God had ordained an irrepressible American mission to accomplish redemption and democratization throughout the world. These claims pushed many Americans, whether they uttered the words manifest destiny or not, to actively seek the expansion of democracy and American culture. These beliefs and the resulting actions were often disastrous to anyone in the way of that mission, as the new religion of American democracy spread on the feet and in the wagons of those who moved west, imbued with the hope that their success would be the nation’s success.

The Young America movement, strongest among members of the Democratic Party but spanning the political spectrum, downplayed divisions over slavery and ethnicity by embracing national unity and emphasizing American exceptionalism, territorial expansion, democratic participation, and economic interdependence. Poet Ralph Waldo Emerson captured the political outlook of this new generation in a speech he delivered in 1844 titled “The Young American”:

In every age of the world, there has been a leading nation, one of a more generous sentiment, whose eminent citizens were willing to stand for the interests of general justice and humanity, at the risk of being called, by the men of the moment, chimerical and fantastic. Which should be that nation but these States? Which should lead that movement, if not New England? Who should lead the leaders, but the Young American?^[1]

Opposition to Expansion

However, many Americans, including Emerson, disapproved of aggressive expansion. For opponents of Manifest Destiny, the lofty rhetoric of the Young Americans was nothing other than a kind of imperialism that the American Revolution was supposed to have repudiated. Many members of the Whig Party (and later the Republican Party) argued that the United States’ mission was to lead by example, not by conquest. Abraham Lincoln summed up this criticism with a fair amount of sarcasm during a speech in 1859:

He [the Young American] owns a large part of the world, by right of possessing it; and all the rest by right of wanting it, and intending to have it. . . . Young America had “a pleasing hope—a fond desire—a longing after” territory. He has a great passion—a perfect rage—for the “new”; particularly new men for office, and the new earth mentioned in the revelations, in which, being no more sea, there must be about three times as much land as in the present. He is a great friend of humanity; and his desire for land is not selfish, but merely an impulse to extend the area of freedom. He is very anxious to fight for the liberation of enslaved nations and colonies, provided, always, they have land. . . . As to those who have no land, and would be glad of help from any quarter, he considers they can afford to wait a few hundred years longer. In knowledge he is particularly rich. He knows all that can possibly be known; inclines to believe in spiritual trappings, and is the unquestioned inventor of “Manifest Destiny.”^[2]

But Lincoln and other anti-expansionists would struggle to win popular opinion. The nation, fueled by the principles of Manifest Destiny, would continue westward. Along the way, Americans battled both Native peoples and foreign nations, claiming territory to the very edges of the continent. But westward expansion did not come without a cost. It pushed the question of slavery to the forefront of American thought, inching the country toward civil war, and, ultimately, threatened the very mission of American democracy it was designed to aid.