If there was one thing the United States did not seem to need in 1803, it was more land. The federal government had plenty to sell settlers in the new state of Ohio and throughout the Old Northwest (stretching from the Ohio and Mississippi rivers to the Great Lakes), as did New York, Pennsyl­vania, and other states. New Englanders were already complaining that the westward exodus was driving up wages and depressing real estate prices in the East.

The United States then consisted of 16 states: the original 13, strung along the Atlantic seaboard, and three recent additions on the frontier: Vermont, which had declared its independence from New York during the Revolution, was finally recognized and admitted in 1791, and Kentucky and Tennessee, carved out of the western reaches of Virginia and North Carolina in 1792 and 1796, respectively, extended the union of states as far as the Mississippi River. The entire area east of the Mississippi had been nominally secured to the United States by the Peace of Paris in 1783, though vast regions remained under the control of Indian nations and subject to the influence of various European imperial powers.

Many skeptical commentators believed that the United States was already too big and that the bonds of union would weaken and snap if new settlements spread too far and too fast. “No paper engagements” could secure the connection of East and West, Massa­chusetts congressman Rufus King wrote in 1786, and separatist movements and disunionist plots kept such concerns alive in subsequent years. Expansionists had a penchant for naturalistic language: At best, the “surge” or “tide” of white settlement might be channeled, but it was ultimately irresistible.

Though President Thomas Jefferson and the American negotiators who secured the Louisiana Purchase in 1803 had not even dreamed of acquiring such a vast territory, stretching from the Mississippi to the Rockies, the expansion of the United States has the retrospective feel of inevitability, however much some modern Americans may be­moan the patriotic passions and imperialistic excesses of “Manifest Destiny” and its “legacies of conquest.” Indeed, it’s almost impossible for us to imagine any other outcome now, or to recapture the decidedly mixed feelings of Americans about their country’s expansion at the start of the 19th century.

Jefferson and his contemporaries understood that they were at a crossroads, and that the American experiment in republican self-government and the fragile federal union on which it depended could easily fail. They understood that the United States was a second-rate power, without the “energy” or military means to project—or possibly even to defend—its vital interests in a world almost constantly at war. And they understood all too well that the loyalties of their countrymen—and, if they were honest with themselves, their own loyalties—were volatile and unpredictable.

There were good reasons for such doubts about American allegiances. Facing an uncertain future, patriotic (and not so patriotic) Americans had only the dimmest sense of who or what should command their loyalty. The Union had nearly collapsed on more than one occasion, most recently during the presidential succession crisis of 1800–01, which saw a tie in the Electoral College and 36 contentious ballots in the House of Representatives before Jefferson was elevated to the presidency. During the tumultuous 1790s, rampant partisan political strife between Federalists and Jefferson’s Repub­licans roiled the nation, and before that, under the Articles of Con­federation (1781–89), the central government ground to a virtual halt and the Union almost withered away before the new constitution saved it. Of course, everyone professed to be a patriot, dedicated to preserving Ameri­can independence. But what did that mean? Federalists such as Alexander Hamilton preached fealty to a powerful, consolidated central government capable of doing the people’s will (as they loosely construed it); Republican oppositionists championed a strictly construed federal constitution that left power in the hands of the people’s (or peoples’) state governments. Each side accused the other of being subject to the corrupt influence of a foreign power: counterrevolutionary England in the case of Federalist “aristocrats” and “monocrats”; revolutionary France for Republican “Jacobins.”

In Jefferson’s mind, and in the minds of his many followers, the new Republican dispensation initiated by his ascension to power in “the Revolution of 1800” provided a hopeful answer to all these doubts and anxieties. Jefferson’s First Inaugural Address, which the soft-spoken, 57-year-old president delivered to Congress in a nearly inaudible whisper in March 1801, seemed to his followers to herald a new epoch in American affairs. “We are all republicans, we are all federalists,” he insisted in the speech. “Let us, then, unite with one heart and one mind.” The president’s inspiring vision of the nation’s future augured, as he told the English radical Joseph Priestley, then a refugee in republican Pennsylvania, something “new under the sun.”

While Jefferson’s conciliatory language in the inaugural address famously helped mend the partisan breach—and, not coincidentally, helped cast Hamilton and his High Federalist minions far beyond the republican pale—it also anticipated the issues that would come to the fore during the period leading up to the Louisiana Purchase.

First, the new president addressed the issue of the nation’s size. Could an expanding union of free republican states survive without jeopardizing the liberties won at such great cost by the revolutionary generation? Jefferson reassured the rising, post-revolutionary generation that it too had sufficient virtue and patriotism to make the republican experiment work and to pass on its beneficent legacy. “Enter­taining a due sense of our equal right to the use of our own faculties” and “enlightened by a benign religion, professed, indeed, and practiced in various forms, yet all of them inculcating honesty, truth, temperance, gratitude, and the love of man; acknowledging and adoring an overruling Providence, which by all its dispensations proves that it delights in the happiness of man here and his greater happiness hereafter,” Americans were bound to be “a happy and a prosperous people.”

Jefferson congratulated his fellow Amer­icans on “possessing a chosen country, with room enough for our descendants to the thousandth and thousandth generation,” a vast domain that was “separated by nature and a wide ocean from the exterminating havoc of one quarter of the globe.” Jefferson’s vision of nationhood was in­scribed on the American landscape: “An overruling Providence, which by all its dispensations proves that it delights in the happiness of man here and his greater happiness hereafter” provided this fortunate people with land enough to survive and prosper forever. But Jefferson knew that he was not offering an accurate description of the nation’s current condition. Given the frenzied pace of westward settlement, it would take only a generation or two—not a thousand—to fill out the new nation’s existing limits, which were still marked in the west by the Mississippi. Nor was the United States as happily insulated from Europe’s “exterminating havoc” as the new president suggested. The Spanish remained in control of New Orleans, the key to the great river system that controlled the continent’s heartland, and the British remained a powerful presence to the north.

Jefferson’s vision of the future was, in fact, the mirror opposite of America’s present situation at the onset of the 19th century. The nation was encircled by enemies and deeply divided by partisan and sectional differences. The domain the president envisioned was boundless, continent-wide, a virgin land waiting to be taken up by virtuous, liberty-loving American farmers. In this providential perspective, Indian nations and European empires simply disappeared from view, and the acquisition of new territory and the expansion of the Union seemed preordained. It would take an unimaginable miracle, acquisition of the entire Louisiana territory, to begin to consummate Jefferson’s inaugural promise.

Jefferson’s expansionist vision also violated the accepted axioms of contemporary political science. In his Spirit of the Laws (1748), the great French philosopher Montesquieu taught that the republican form of government could survive only in small states, where a virtuous and vigilant citizenry could effectively monitor the exercise of power. A large state, by contrast, could be sustained only if power were concentrated in a more energetic central government; republicanism in an expanding state would give way to more “despotic,” aristocratic, and monarchical regimes. This “law” of political science was commonly understood in mechanical terms: Centri­fugal forces, pulling a state apart, gained momentum as territory expanded, and they could be checked only by the “energy” of strong government.

James Madison had grappled with the problem in his famous Federalist 10, in which he argued that an “extended republic” would “take in a greater variety of parties and interests,” making it “less probable that a majority of the whole will have a common motive to invade the rights of other citizens.” Modern pluralists have embraced this argument, but it was not particularly persuasive to Madison’s generation—or even to Madison himself a decade later. During the struggle over ratification of the Constitution, Antifederalists effectively in­voked Montes­quieu’s dictum against Feder­alist “consolidationism,” and in the 1790s, Jeffersonian defenders of states’ rights offered the same arguments against Hamil­tonian High Federalism. And Jefferson’s “Revolution of 1800,” vindicating the claims of (relatively) small state-republics against an overly energetic central government, seemed to confirm Montes­quieu’s wisdom. Montesquieu’s notion was also the basis for the popular interpretation of what had caused the rise of British tyranny in the colonies before the American Revol­ution.

At the same time, however, Montes­quieu’s logic posed a problem for Jefferson. How could he imagine a continental republic in 1801 and negotiate a land cession that doubled the country’s size in 1803? To put the problem somewhat differently, how could Jefferson—who had, after all, drafted the controversial Kentucky Resolutions of 1798, which threatened state nullification of federal authority—overcome his own disunionist tendencies?

Jefferson’s response in his inaugural was to call on his fellow Americans to “pursue our own federal and republican principles, our attachment to union and representative government,” with “courage and confidence.” In other words, a sacred regard for states’ rights (“federal principles”) was essential to the preservation and strength of a “union” that depended on the “attachment” of a people determined to secure its liberties (“republican principles”). This conception of states as republics would have been familiar and appealing to many Americans, but Jeffer­son’s vision of the United States as a powerful nation, spreading across the continent, was breathtaking in its boldness. How could he promise Americans that they could have it both ways, that they could be secure in their liberties yet have a federal government with enough “energy” to preserve itself? How could he believe that the American government, which had only recently endured a near-fatal succession crisis and which had a pathetically small army and navy, was “the strongest Government on earth”?

Jefferson responded to these questions resoundingly by invoking—or perhaps more accurately, inventing—an American people or nation, united in devotion to common principles, and coming together over the course of succeeding generations to constitute one great family. Thus, the unity the president imagined was prospective. Divided as they might now be, Americans would soon come to realize that they were destined to be a great nation, freed from “the throes and convulsions of the ancient world” and willing to sacrifice everything in defense of their country. In Jefferson’s vision of progressive continental development, the defensive vigilance of virtuous republicans, who were always ready to resist the encroachments of power from any and every source, would be transformed into a patriotic devotion to the transcendent community of an inclusive and expanding nation, “the world’s best hope.” “At the call of the law,” Jefferson predicted, “every man . . . would fly to the standard of the law, and would meet invasions of the public order as his own personal concern.”

Jefferson thus invoked an idealized vision of the American Revolution, in which patriotic citizen-soldiers rallied against British tyranny, as a model for future mobilizations against internal as well as external threats. (It was an extraordinary—and extraordinarily influential—exercise in revisionist history. More dis­passionate observers, including those who, unlike Jefferson, actually had some military experience, were not inclined to give the militias much, if any, credit for winning the war.)

Jefferson’s conception of the American nation imaginatively countered the centrifugal forces, the tendency toward anarchy and disunion, that republicanism authorized and unleashed. Devotion to the Union would reverse this tendency and draw Amer­icans together, even as their private pursuits of happiness drew them to the far frontiers of their continental domain. It was a paradoxical, mystifying formulation. What seemed to be weakness—the absence of a strong central government—was, in fact, strength. Expansion did not attenuate social and political ties; rather, it secured a powerful, effective, and affective union. The imagined obliteration of all possible obstacles to the enactment of this great national story—the removal of Indians and foreigners—was the greatest mystification of all, for it disguised how the power of the federal state was to be deployed to clear the way for “nature’s nation.”

In retrospect, the peaceful acquisition of the Louisiana Territory, at the bargain-basement price of $15 million, seemed to conform to the expansionist scenario in Jefferson’s First Inaugural Adddress. The United States bought land from France, just as individuals bought land from federal and state land offices, demonstrating good intentions (to be fruitful and multiply, to cultivate the earth) and their respect for property rights and the rule of law. Yet the progress of settlement was inexorable, a “natural” force, as the French wisely recognized in ceding their claims.

The threat of armed conflict was, nonetheless, never far below the surface. When the chilling news reached America in 1802 that Spain had retroceded Louisiana to France, under pressure from Napoleon Bonaparte, some Federalists agitated for a preemptive strike against New Orleans before Napoleon could land troops there and begin to carry out his plan for a reinvigorated French empire in the Western Hemisphere. As if to provide a taste of the future, Spanish authorities in New Or­leans revoked the right of American traders to store goods in the city for export, thereby sending ripples of alarm and economic distress through farms and plantations of the Missis­sippi valley. Americans might like to think, with Jefferson, that the West was a vast land reserve for their future generations, but nature would issue a different decree if the French gained control of the Mississippi River system.

As Senator William Wells of Delaware warned the Senate in February 1803, if Napoleon were ensconced in New Orleans, “the whole of your Southern States” would be at his mercy; the French ruler would not hesitate to foment rebellion among the slaves, that “inveterate enemy in the very bosom of those States.” A North Carolina congressman expected the French emperor to do even worse: “The tomahawk of the savage and the knife of the negro would confederate in the league, and there would be no interval of peace.” Such a confederation—a powerful, unholy alliance of Europeans, Indians, and slaves—was the nightmarish antithesis of the Americans’ own weak union. The French might even use their influence in Congress to revive the vicious party struggles that had crippled the national government during the 1790s.

Jefferson had no idea how to respond to the looming threat, beyond sending his friend and protégé James Monroe to join U.S. Minister to France Robert R. Living­ston in a desperate bid to negotiate a way out of the crisis. At most, they hoped that Napoleon would sell New Orleans and the Floridas to the United States, perhaps with a view to preempting an Anglo-American alliance. Jefferson dropped a broad hint to Livingston (undoubtedly for Napoleon’s edification) that if France ever took “possession of N. Orleans . . . we must marry ourselves to the British fleet and nation.” For the Anglophobe Jefferson this must have been a horrible thought, even if it was a bluff. But then, happily for Jefferson—and crucially for his historical reputation—fortune intervened.

Napoleon’s intentions for the New World hinged on control of Saint-Domingue (now Haiti), but a slave revolt there, led by the brilliant Toussaint L’Ouverture, complicated the emperor’s plans. With a strong assist from yellow fever and other devastating diseases, the rebels fought a French expeditionary force of more than 20,000 to a standstill. Thwarted in his western design and facing the imminent resumption of war in Europe, Napoleon decided to cut his losses. In April 1803, his representative offered the entire Louisiana Territory to a surprised Livingston. By the end of the month, the negotiators had arrived at a price. For $15 million, the United States would acquire 828,000 square miles of North America, stretching from the Mississippi River to the Rocky Mountains and from the Gulf of Mexico to the Canadian border. Over time 13 states would be carved from the new lands.

When the news reached America in July, it proved a great deal more than anyone had been contemplating but was met with general jubilation. There was widespread agreement that national security depended on gaining control of the region around New Orleans;  and Spanish Florida, occupying the critical area south of Georgia and the territory that the state had finally ceded to Congress in 1802, was high on southern planters’ wish list of territorial acquisitions. But it was hard to imagine any immediate use for the trans-Mississippi region, notwithstanding Jeffer­son’s inspiring rhetoric, and there was some grumbling that the negotiators had spent more than Congress had authorized. A few public figures, mostly New England Fed­eralists, even opposed the transaction on political and constitutional grounds.

The Lewis and Clark expedition, authorized before the Purchase was completed, testifies to Americans’ utter ignorance of the West in 1803. The two explorers were sent, in effect,  to feel around in the dark. Perhaps, Jef­fer­son mused, the trans-Mississippi region could be used as a kind of toxic waste dump, a place to send emancipated slaves beyond harm’s way. Or, a more portentous thought, Indian nations might be relocated west of the river—an idea President Andrew Jackson later put into effect with his infamous removal policy.

What gripped most commentators as they celebrated the news of the Purchase in 1803 was simply that the Union had survived another awful crisis. They tended to see the new lands as a buffer. “The wilderness itself,” Repre­sentative Joseph Nicholson of Mary­land exclaimed, “will now present an almost insurmountable barrier to any nation that inclined to disturb us in that quarter.” And another congressman exulted that America was now “insulated from the rest of the world.”

David Ramsay, the South Carolina historian and devout Republican, offered the most full-blown paean to the future of the “chosen country” as Jefferson had envisioned it. Echoing Jefferson’s First Inaug­ural, he asked, “What is to hinder our extension on the same liberal principles of equal rights till we have increased to twenty-seven, thirty-seven, or any other number of states that will conveniently embrace, in one happy union, the whole country from the Atlantic to the Pacific ocean, and from the lakes of Canada to the Gulf of Mexico?” In his Second Inaugural, in 1805, Jefferson himself would ask, “Who can limit the extent to which the federative principle may operate effectively?” Gone were his doubts about the uses to which the new lands could be put. “Is it not better that the opposite bank of the Mississippi should be settled by our own brethren and children, than by strangers of another family?”

Jefferson’s vision of the American future has ever since provided the mythic master narrative of American history. In the western domains that Jefferson imagined as a kind of blank slate on which succeeding generations would inscribe the image of American nationhood, it would be all too easy to overlook other peoples and other possibilities. It would be all too easy as well to overlook the critical role of the state in the progress of settlement and development. When Americans looked back on events, they would confuse effects  with causes: War and diplomacy eliminated rival empires and dispossessed native peoples; an activist federal state played a critical role in pacifying a “lawless” frontier by privatizing public lands and promoting economic development. In the mythic history of Jefferson’s West, an irresistible westward tide of settlement appears to be its own cause, the manifest destiny of nature’s nation.

Yet if the reality of power remains submerged in Jefferson’s thought, it’s not at any great depth. The very idea of the nation implies enormous force, the power of a people enacting the will of “an overruling Providence.” In Jefferson’s Declaration of Independence, Americans claimed “the separate & equal station to which the laws of nature and of nature’s God entitle them.” The first law of nature, the great natural law proclaimed by writers of the day, was self-preservation, and the defining moment in Amer­ican history was the great mobilization of American power to secure independence in the Revolution. President Jefferson’s vision of westward expansion projected that glorious struggle into the future and across the continent. It was a kind of permanent revolution, reenacting the nation’s beginnings in the multiplication of new, self-governing republican states.

Born in war, Jefferson’s conception of an expanding union of free states constituted a peace plan for the New World. But until it was insulated from Europe’s “exterminating havoc,” the new nation would remain vulnerable, unable to realize its historic destiny. By eliminating the clear and present danger of a powerful French presence at the mouth of the Mississippi, the Louisiana Purchase guaranteed the survival of the Union—for the time being, at least. By opening the West to white American settlers, it all but guaranteed that subsequent generations would see their own history in Jefferson’s vision of their future, a  mythic, nation-making vision yoking individual liberty and national power and promising a future of peace and security in a dangerous world. Two hundred years later, that vision  re­mains compelling to many Amer­icans.