In the summer of 1845, a New York newspaper editor reached for a phrase that would echo across a continent — and across centuries. What he called America’s manifest destiny was not a new idea but an old hunger finally given a name, one that would justify wars, displace millions, and redraw the map of North America in less than a generation. To understand how three words acquired such power, you have to start not in 1845 but more than three centuries earlier.
The Theological Seed: The Doctrine of Christian Discovery (1493)
In 1493, Pope Alexander VI issued a papal bull declaring that Christian nations held the divine right to claim any lands inhabited by non-Christians. It was a legal and religious framework dressed in the language of heaven — and it would do tremendous earthly work in the centuries that followed. English colonists who crossed the Atlantic carried this doctrine in their cultural luggage, treating Indigenous territories as essentially vacant, available by God’s own grant to those who would “improve” them.
Manifest destiny was not conjured from thin air in 1845 — it crystallized an ideology with roots stretching back more than three and a half centuries. The Doctrine of Christian Discovery gave expansionism its first sacred sanction, embedding the assumption of Indigenous dispossession so deeply into colonial law and theology that later generations would barely notice they were inheriting it. That inheritance made the eventual phrase feel less like a policy choice and more like a natural fact — which was precisely the point.
John Winthrop’s ‘City Upon a Hill’ and the Birth of American Exceptionalism (1630)
On board the ship Arbella, crossing the Atlantic toward Massachusetts in 1630, Puritan governor John Winthrop delivered a sermon that would resonate far beyond its moment. He told his followers that their new colony would be a “city upon a hill” — a beacon of godly civilization watched by all the world. It was a powerful fusion of religious mission and territorial purpose: the idea that these particular people, in this particular place, had been chosen by Providence for something extraordinary.
That sense of divine election became the emotional engine behind westward expansion two centuries later. When 19th-century politicians argued that America was destined by God to stretch from sea to sea, they were drawing directly on a current of belief that Winthrop had helped set in motion. The language changed; the underlying claim — that Anglo-American settlers occupied a uniquely favored position in God’s plan — did not. Exceptionalism, once planted, grows deep roots.
Jefferson Eyes the Continent and Commissions Lewis and Clark (1803-1806)
In the spring of 1803, President Thomas Jefferson completed the Louisiana Purchase, roughly doubling the size of the United States with the addition of some 828,000 square miles for approximately $15 million — about four cents an acre. It was a staggering act of territorial imagination, and Jefferson wasted no time making it tangible. He dispatched Meriwether Lewis and William Clark westward to map the new territory, identify its resources, and scout a route to the Pacific, explicitly envisioning a republic that would one day span the continent.
The expedition returned in 1806 laden with journals, botanical specimens, and painstakingly drawn maps. For American audiences, the effect was transformative: the vast interior of North America, so long a rumor and a mystery, suddenly felt knowable — and therefore claimable. Jefferson had not yet given expansion a catchy name, but he had given it something more durable: a detailed blueprint and a sense of continental entitlement backed by federal authority.
Indian Removal: Federal Policy Puts Dispossession Into Law (1830)
Fifteen years before O’Sullivan coined his famous phrase, the logic it would later dress in poetic language was already being written into federal statute. The Indian Removal Act of 1830, signed by President Andrew Jackson, authorized the forced relocation of Indigenous nations from their ancestral homelands in the American Southeast to territory west of the Mississippi River. The Cherokee, Choctaw, Creek, Chickasaw, and Seminole nations — the so-called Five Civilized Tribes — were compelled to abandon lands their communities had occupied for generations.
The Cherokee removal of 1838-1839, which the Cherokee Nation calls the Trail of Tears, alone killed an estimated 4,000 people from exposure, disease, and starvation during the forced march west. Indian removal demonstrated that manifest destiny was not merely a rhetorical posture — it was a program of ethnic dispossession enforced by the United States Army, a full decade before the ideology acquired its most famous name.
John L. O’Sullivan Coins the Phrase (July 1845)
The man who coined manifest destiny was not a general or a president but a prolific, combative New York journalist named John L. O’Sullivan. Writing in the United States Magazine and Democratic Review in July 1845, O’Sullivan argued that it was America’s “manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.” He was writing specifically to defend the annexation of Texas, and his framing was deliberate: expansion was not conquest, he insisted, but inevitability — a God-given right written into the nature of the republic itself.
O’Sullivan gets the credit for the phrase, though some historians have traced similar language to earlier decades, and the hunger the words described had existed for generations before he found them. What he achieved was a kind of ideological shorthand — three words that could compress an entire worldview into a headline, and that politicians and editorial writers would reach for again and again in the years that followed. The phrase worked precisely because it transformed a contested political choice into something that felt as inevitable as sunrise.
The Annexation of Texas Triggers War with Mexico (1845-1848)
The United States formally annexed the Republic of Texas in December 1845, a move Mexico regarded as an act of outright aggression against territory it still considered its own. President James K. Polk, one of the most unapologetically expansionist figures ever to occupy the White House, had been waiting for exactly such a confrontation. When a skirmish broke out along the disputed Rio Grande border in the spring of 1846, Polk went before Congress claiming that Mexico had shed American blood on American soil, and a declaration of war followed.
The Mexican-American War ended in 1848 with the Treaty of Guadalupe Hidalgo, and the terms were staggering: Mexico was compelled to cede roughly 525,000 square miles — the land that would become California, Nevada, Utah, Arizona, New Mexico, Colorado, and Wyoming — in exchange for $15 million. In the span of three years, the ideology of manifest destiny had translated directly into one of the largest territorial transfers in the history of the Western Hemisphere. Critics in Congress, including a freshman representative from Illinois named Abraham Lincoln, questioned Polk’s account of where the first shots had been fired — but the land had already changed hands.
The Oregon Treaty Settles the Pacific Northwest Without a Shot (1846)
While American and Mexican soldiers were dying in the deserts of the Southwest, President Polk was simultaneously pressing a second territorial claim on the opposite side of the continent. The Oregon Territory had been under joint British and American occupation since 1818, a diplomatic ambiguity that suited neither power indefinitely. Polk, whose 1844 campaign had rallied around the slogan “Fifty-Four Forty or Fight,” ultimately settled for pragmatism over bluster, negotiating the Oregon Treaty of 1846 with Britain and fixing the U.S.-Canada border at the 49th parallel.
The agreement handed the United States the future states of Oregon, Washington, and Idaho, securing the Pacific coastline from the north. Manifest destiny thus achieved its continental reach on two separate fronts within the same remarkable two-year window — one through war, one through negotiation — permanently redrawing the political map of North America. The contrast between the two methods is instructive: the ideology was flexible enough to accommodate both, so long as the territory was gained.
Gold, the Transcontinental Railroad, and the Flood of Settlers Into Indigenous Homelands (1848-1869)
The ink on the Treaty of Guadalupe Hidalgo was barely dry when, just nine days before its signing, a carpenter named James Marshall spotted flecks of gold in the millrace at Sutter’s Mill in California. The news spread with extraordinary speed, and by 1855 some 300,000 migrants had poured into California from across the United States and around the world. The Gold Rush transformed a distant territory into a churning, chaotic society almost overnight — and it placed crushing pressure on the Indigenous nations whose homelands now lay in the path of hundreds of thousands of newcomers backed, when necessary, by the U.S. Army.
Settler expansion brought broken treaties, forced removals, and systematic violence against dozens of Indigenous peoples across the West. The ideology of manifest destiny provided the justification while federal policy provided the mechanism. When the First Transcontinental Railroad was completed in 1869, driving its ceremonial golden spike at Promontory Summit in Utah, it transformed manifest destiny from an editorial argument into infrastructure. Mass migration was now not just possible but structurally inevitable, and the continent was stitched together on American terms — terms that left little room for the nations already there.
John Gast Paints American Progress — Manifest Destiny Gets Its Defining Image (1872)
If O’Sullivan gave manifest destiny its words, painter John Gast gave it its face. In 1872, Gast produced an allegorical canvas titled American Progress, depicting a towering, luminous angelic figure floating serenely westward across the landscape, trailing telegraph wire from her fingers as she advanced. Behind her, bathed in golden light, came covered wagons, stagecoaches, farmers, and railroad trains. Before her, retreating into darkness at the painting’s left edge, fled buffalo, bears, and Indigenous peoples.
The painting was reproduced widely as a chromolithograph and distributed across the country, becoming for many Americans the primary visual vocabulary through which they understood westward expansion. Its power lay in its brutal simplicity: progress moved in one direction, light replaced darkness, civilization displaced wilderness. That the “wilderness” was home to living nations with their own histories, laws, and futures was a fact the painting rendered literally invisible — pushed off the canvas into the dark. That invisibility was not an accident; it was the argument.
Frederick Jackson Turner Declares the Frontier Closed — and Enshrines the Myth (1893)
At the 1893 World’s Columbian Exposition in Chicago — an event staging America’s triumph at the very moment it was mourning a loss — a young historian from Wisconsin named Frederick Jackson Turner delivered a paper that would reshape how Americans understood themselves for generations. His “Frontier Thesis” argued that the American character — its restlessness, its democratic instincts, its rugged individualism — had been forged by the perpetual experience of the western frontier. And now, Turner announced, citing the 1890 census, that frontier was gone. The continent had been fully claimed.
Turner’s thesis did two things simultaneously: it enshrined manifest destiny as the foundational narrative of American identity, and it elegized that narrative just as it was being completed. It also performed a remarkable erasure, treating the land as empty wilderness conquered by pioneer spirit rather than as a vast network of Indigenous homelands taken by force. For decades, his framework dominated how manifest destiny history was taught in American schools — which meant that the framework’s blind spots were passed along as settled truth to successive generations of students.
Historians and Indigenous Scholars Force a Reckoning (20th-21st Century)
By the latter decades of the 20th century, a new generation of historians — joined increasingly by Indigenous scholars speaking from their own communities’ living memory — began the hard work of dismantling the triumphalist version of the story. They documented the scale of what manifest destiny had actually produced: the Trail of Tears and other forced removals, military massacres at Sand Creek in Colorado in 1864 and at Wounded Knee in South Dakota in 1890, and the deliberate destruction of the bison herds on which Plains nations depended for survival. The California Gold Rush alone, they documented, reduced the state’s Indigenous population from an estimated 150,000 in 1845 to fewer than 30,000 by 1870 — a collapse driven by violence, disease, and starvation.
These scholars argued that the manifest destiny origin story had always functioned as a cover story — one that made a deliberate, systematic policy of dispossession look like the natural unfolding of Providence. Today, manifest destiny is understood as both a historical phenomenon and a cautionary study in how providential language can be weaponized — how the rhetoric of divine mission can make conquest feel like destiny and victims feel like obstacles to someone else’s story. The debate over its legacy continues in classrooms, in treaty rights litigation, and in arguments about whose version of American history gets taught at all.
From a papal decree in 1493 to a newspaper column in 1845 to courtrooms in the 21st century, the story of manifest destiny is ultimately a story about how ideas justify power — and about how long it can take for the people most harmed by those ideas to make the reckoning impossible to ignore.
