The Louisiana Purchase's effect upon the American political landscape was almost as dramatic as its effect upon the country's geography.
In 1803, the democratic experiment of the American republic remained very much in its infancy. The Constitution had been ratified just over a decade earlier. Only four new states (Vermont, Kentucky, Tennessee, and Ohio) had joined the original thirteen in the Union. Thomas Jefferson was only the third president; his election in 1800 was the very first peaceful transfer of power from the incumbent party (John Adams's Federalists) to the opposition (Jefferson's Democratic-Republicans).
The Louisiana Purchase literally expanded the horizons of American opportunity, but it also raised thorny political and constitutional questions for the country's fragile young democracy.
The first problem was the Purchase's constitutionality. Nowhere does the Constitution authorize the executive branch of the government to spend public funds to expand the boundaries of the nation. This was problematic for Jefferson, who had been elected behind a political philosophy that emphasized small government, low taxes, and "strict construction" of the Constitution—in other words, adhering rigidly to the Tenth Amendment's stricture that all "powers not delegated to the United States by the Constitution... are reserved to the States respectively, or to the people." During the 1790s, Jefferson had fought vigorously against Alexander Hamilton's Federalist plan to charter a National Bank, since the Constitution delegated no specific bank-chartering powers to the government and Jefferson rejected Hamilton's argument that such powers were "implied" by the Constitution.
So by Jefferson's own standards, the Louisiana Purchase was clearly unconstitutional. When he received word of the Purchase from his emissaries in Paris, Jefferson first response was to draft a proposed constitutional amendment that would have legitimized his actions by authorizing the president explicitly to purchase new territory. However, fearing the amendment would not pass in time to ratify the treaty, Jefferson quickly abandoned his plans for amending the Constitution, instead taking the easier (if more hypocritical) path of claiming the power to acquire territory was "implied" in the Constitution's clause on treaty-making.
Jefferson's flip-flop on "strict construction" and implied powers could be seen as a straightforward abandonment of principle for power. Jefferson's own rationalization for the decision was less than entirely convincing, offering little to counter the perception that simple expediency had carried the day: "It is the case," he said, " of a guardian, investing the money of his ward in purchasing an important adjacent territory; and saying to him when of age, I did this for your own good."6 For Jefferson—normally a staunch defender of individual liberty—to resort to an analogy casting the American people as ward of the state was almost shocking.
For Federalists, Jefferson's move appeared even more dubious in light of the clear partisan advantage his ruling Democratic-Republicans would gain from the territorial expansion. American politics at the time broke along heavily regional lines; Federalists won support almost entirely from commerce-friendly New England, while Democratic-Republicans drew strength from agrarian voters in the South and West. (Voters west of the Appalachian Mountains never elected a single Federalist to national office.) The Louisiana Purchase, by adding immense new Southern and Western territories—and eventually, new Southern and Western states—promised to boost Democratic-Republican representation in Congress, lifting Jefferson's party into permanent majority status. (Federalist fears in this regard were not unfounded; indeed, by the late 1810s, the Federalists had disintegrated as a national party and Democratic-Republicans achieved virtual one-party rule.)
While the Louisiana Purchase therefore gave a strong (if regrettably unconstitutional) boost to the electoral prospects of Jefferson's party, its legacy for Jefferson's grand vision of an "empire of liberty" was much more ambiguous. Jefferson believed that the best way to guarantee the long-term integrity of the republic was to cultivate a nation of independent yeoman farmers. Jefferson's idealized farmer, owning his own plot of land and dependent upon no one else for his sustenance, would fight corruption and maintain liberty. But Jefferson's yeoman republic could not survive a shortage in free land; once a country was full, men without land would be required to work for others, and their loss of economic independence would lead to a loss of political independence as well. So Jefferson hoped that the Louisiana Purchase, by doubling the size of the United States, would provide generations' worth of free land to extend the yeoman republic's "empire of liberty" toward the western horizon.
Yet Jefferson himself was no yeoman farmer, but rather an aristocratic, slave-owning planter. While he famously declared that "those who labor in the earth are the chosen people of god,"7 Jefferson himself rarely labored on his own estate; his slaves did. And the new lands of the Louisiana Purchase would ultimately allow for the massive expansion of not only the family farm but also of the slaveocracy. The tension in Jefferson's own life between the yeoman ideal and the slave-labor reality would play out, at a national scale, through a half century of conflict between pro- and anti-slavery settlers in the Louisiana Territory.
The question of slavery in the western lands would become the most contentious problem in antebellum American politics. Northern advocates of free labor and Southern defenders of slavery each sought victory through the Western expansion of their respective labor systems. If the new states that emerged from the Louisiana Territory were all free, for example, then the balance of power in the U.S. Senate would tilt decisively against slavery. Or vice versa. Thus the problem of slavery in the West fueled a series of dire sectional crises in Washington. From the Missouri Compromise to the Kansas-Nebraska Act to the Dred Scot decision, the ugly flashpoints leading toward the Civil War often centered on the Louisiana Territory.