Thomas Jefferson and the Louisiana Purchase

Full color drawing of the Louisiana Purchase map.
Vintage map of the Louisiana Purchase in 1803.

GraphicaArtis/Getty Images

The Louisiana Purchase was one of the largest land deals in history. In 1803, the United States paid approximately $15 million dollars to France for more than 800,000 square miles of land. This land deal was arguably the greatest achievement of Thomas Jefferson's presidency, but it also posed a major philosophical problem for Jefferson.​

Thomas Jefferson, the Anti-Federalist

Thomas Jefferson was strongly anti-federalist. Although he participated in the writing of the Declaration of Independence, he did not author the Constitution. Instead, the Constitution was mainly written by Federalists such as James Madison. Jefferson spoke against a strong federal government and instead advocated states' rights. He feared tyranny of any kind and only recognized the need for a strong, central government in terms of foreign affairs. He was concerned that the Constitution did not address the liberties that were protected by the Bill of Rights and did not call for term limits for the president.

Jefferson's philosophy regarding the role of the central government is most clearly seen when investigating his disagreement with Alexander Hamilton over the creation of a national bank. Hamilton was a staunch supporter of a strong central government. A national bank was not expressly mentioned in the Constitution, but Hamilton thought that the elastic clause (U.S. Const. art. I, § 8, cl. 18) gave the government the power to create such a body. Jefferson completely disagreed. He held that all powers given to the national government were enumerated or expressed. If they were not expressly mentioned in the Constitution, then they were reserved to the states.

Jefferson's Compromise

In completing the Louisiana Purchase, Jefferson had to put aside his principles because this type of transaction was not expressly mentioned in the Constitution. Had he waited for a constitutional amendment, however, the deal might have fallen through. With the support of the American people, Jefferson decided to go through with the purchase.

Jefferson needed to move quickly when he discovered that Spain had signed a secret treaty with France in 1801 ceding Louisiana to France. France suddenly posed a potential threat to America. The fear was that if America did not purchase New Orleans from France, it could lead to war.

The change of ownership from Spain to France resulted in the closure of the port's warehouses to Americans, and it was feared that France would move to cut off America's access to the port entirely. Jefferson sent envoys to France to try to secure the purchase of New Orleans. Instead, they returned with an agreement to buy the entire Louisiana Territory as Napoleon needed money for the impending war against England.

Importance of the Louisiana Purchase

With the purchase of this new territory, the land area of America nearly doubled. However, the exact southern and western boundaries were not defined in the purchase. America would have to work with Spain to negotiate the specific details of these boundaries.

When Meriwether Lewis and William Clark led a small expeditionary group called the Corps of Discovery into the territory, this was just the beginning of America's fascination with exploring the West. Whether or not America had a "Manifest Destiny" to span from "sea to sea" as was often the rallying cry of the early to mid-19th century, its desire to control this territory cannot be denied.


  • “Louisiana Purchase, The.” Monticello, Thomas Jefferson Foundation, Inc.,
  • Mullen, Pierce. “Financing the Purchase.” Discovering Lewis & Clark®, Lewis & Clark Fort Mandan Foundation, Lewis & Clark Trail Heritage Foundation, and the National Park Service Lewis and Clark National Historic Trail,
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Kelly, Martin. "Thomas Jefferson and the Louisiana Purchase." ThoughtCo, Feb. 16, 2021, Kelly, Martin. (2021, February 16). Thomas Jefferson and the Louisiana Purchase. Retrieved from Kelly, Martin. "Thomas Jefferson and the Louisiana Purchase." ThoughtCo. (accessed March 30, 2023).