Wondering how the U.S. doubled in size with one deal? These Louisiana Purchase facts give you the short answer: in 1803 France sold about 828,000 square miles to the United States for $15 million.
This guide sits in our us history section, where you can follow other turning points in the American story.
| Item | Key fact |
|---|---|
| Territory acquired | About 828,000 square miles |
| Total price | $15 million ($11,250,000 plus $3,750,000 in assumed claims) |
| Treaty dated and signed | Dated April 30, 1803; signed May 2, 1803 |
| Senate approval | Later that October |
| Price per acre | Less than three cents |
| States later formed | Part or all of 15 states |
The figures come from HISTORY.com’s Louisiana Purchase overview and the Council on Foreign Relations. Historical figures can change as sources are revised, so check the source before you rely on them.
Why did the United States want New Orleans?
The story starts with trade, not land. Americans living west of the Appalachians depended on the Mississippi River to send their goods to market, as the Council on Foreign Relations explains.
A 1795 treaty with Spain let U.S. merchants and farmers send goods down the river and store them in New Orleans without paying export duties, according to HISTORY.com. That “right of deposit” kept western farms connected to the world. The trouble began when Louisiana changed hands again.
Here is how the territory’s ownership shifted, per HISTORY.com, its overview and the Council on Foreign Relations:
- In 1682, explorer Robert Cavelier de La Salle claimed the territory for France and named it for King Louis XIV.
- In 1762, France ceded Louisiana west of the Mississippi River to Spain.
- In 1800, Napoleon Bonaparte pressured Spain to sign the secret Treaty of San Ildefonso.
- In October 1802, Spain formally handed its claim to France and, in the same month, the right of deposit was revoked.
Thomas Jefferson saw the danger at once. He called French control of Louisiana “the embryo of a tornado” that would burst on both sides of the Atlantic, as the Council on Foreign Relations records.
How the deal came together in Paris
Jefferson chose diplomacy over force. In January 1803 he sent his friend James Monroe to Paris, with instructions to buy New Orleans and as much of the land east of the city as possible. He authorized Monroe to spend up to $10 million, according to the Council on Foreign Relations.
The Americans never asked for all of Louisiana, as HISTORY.com notes. Napoleon dangled the entire territory in front of them on April 11, 1803. Monroe reached Paris on April 12, 1803, and found the offer already on the table, per the Council on Foreign Relations.
Why would Napoleon sell? Several pressures stacked up, according to HISTORY.com and the Council on Foreign Relations:
- A French expedition to retake Saint Domingue, today’s Haiti, collapsed, and many French soldiers died of yellow fever.
- War with Britain loomed, and a British naval blockade of France was probable.
- France faced economic difficulties and needed cash.
Napoleon wanted the money immediately in order to prepare for war with Great Britain, per HISTORY.com. He also saw a strategic upside. In the Council on Foreign Relations account, he said the sale gave England “a maritime rival that sooner or later will lay low her pride.”
What the United States paid and received
The treaty was dated April 30 and signed on May 2, per HISTORY.com. The territory stretched from the Mississippi River to the Rocky Mountains and from the Gulf of Mexico to the Canadian border. In return, the U.S. envoys agreed to pay $11,250,000 and assume claims of American citizens against France worth $3,750,000.
Those two pieces add up to the headline price. The same overview calls it a bargain at less than three cents an acre.
Even that bargain strained the young country. According to HISTORY.com, the United States had to borrow from two European banks at six percent interest. It did not finish repaying the loan until 1823, by which time the total cost had risen to over $23 million.
Jefferson’s constitutional dilemma
News of the deal was announced on July 4, 1803, and most Americans applauded, as the Council on Foreign Relations reports. Jefferson, however, had long argued that the federal government could do only what the Constitution explicitly allowed. The Constitution made no provision for acquiring foreign territory.
According to Encyclopedia.com, Jefferson called the treaty “an act beyond the Constitution” and drafted a 375-word amendment. When congressmen worried that Louisiana might be lost over constitutional scruples, he went along with the treaty anyway.
He later told others privately, “The less we say about constitutional difficulties the better,” as HISTORY.com records. The Senate approved the treaty on October 20, 1803.
Not everyone cheered. Members of the Federalist Party worried the purchase would further reduce their clout, according to HISTORY.com. The boundaries were also unclear, and Encyclopedia.com notes that people asked whether Texas or West Florida were included. The Supreme Court later upheld the power to acquire and govern territory in a case from 1828.
What the Louisiana Purchase changed
France transferred authority over the region in December 1803, and a territorial government followed in 1804, per HISTORY.com. Jefferson soon commissioned the Lewis and Clark Expedition to explore the new land. On April 30, 1812, Louisiana became the 18th state, and part or all of 15 states were eventually created from the purchase.
The land was not empty. As HISTORY.com notes, Native Americans had inhabited the area for generations, and the treaty was struck without them.
The treaty also raised a question about belonging. Encyclopedia.com says Article III held that the inhabitants should be incorporated in the Union and enjoy all the rights of citizens. For how the struggle over those rights played out in later generations, see our civil rights movement timeline.
Historians still rate the deal highly. A survey of members of the Society for Historians of American Foreign Relations ranked it the fourth-best foreign policy decision in U.S. history, according to the Council on Foreign Relations. To see how the young republic got started, read our american revolution timeline.
Frequently asked questions
How much did the Louisiana Purchase cost?
Show answer
The headline price was $15 million, according to the Council on Foreign Relations. HISTORY.com breaks that into $11,250,000 in payment and $3,750,000 in assumed claims.
How big was the Louisiana Purchase?
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It brought in about 828,000 square miles of territory, which doubled the size of the young republic, per HISTORY.com.
When was the Louisiana Purchase signed and ratified?
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The treaty was dated April 30, 1803 and signed on May 2, according to HISTORY.com. The Senate approved it on October 20, 1803, per HISTORY.com’s October 20 entry.
Did Jefferson think the purchase was constitutional?
Show answer
He had doubts. Encyclopedia.com says he called the treaty “an act beyond the Constitution” and drafted a 375-word amendment before he accepted the treaty without one.
What was the first state formed from the territory?
Show answer
Louisiana, admitted on April 30, 1812 as the 18th U.S. state, according to HISTORY.com.
