Louisiana Purchase

American  

noun

U.S. History.

1. a treaty signed with France in 1803 by which the U.S. purchased for $15,000,000 the land extending from the Mississippi River to the Rocky Mountains and from Canada to the Gulf of Mexico.

2. the land included in this purchase.

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Louisiana Purchase British  

noun

1. the large region of North America sold by Napoleon I to the US in 1803 for 15 million dollars: consists of the W part of the Mississippi basin. Area: about 2 292 150 sq km (885 000 sq miles)

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Louisiana Purchase Cultural  

1. The purchase by the United States from France of the huge Louisiana Territory in 1803. President Thomas Jefferson ordered the purchase negotiations, fearing that the French, then led by Napoleon, wanted to establish an empire in North America. The French had no such ambitions but were happy to exchange their vast landholdings for cash. The area that they sold, extending from the Mississippi River to the Rocky Mountains, more than doubled the size of the United States.

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Example Sentences

President Thomas Jefferson acquired the 828,000-square-mile Louisiana Purchase in 1803 for $15 million, or about $18 per square mile.

From Barron's • Jan. 8, 2026

The U.S. is exceptional in the extent to which it has expanded through land purchases, starting with the Louisiana Purchase of 1803.

From The Wall Street Journal • Jan. 7, 2026

When the U.S. acquired these lands through the Louisiana Purchase, the Oregon Treaty and the Mexican-American War, there were no states in these areas to manage vast tracts of land.

From Salon • Jun. 21, 2025

A critical gateway between the Mississippi River and global oceans, New Orleans has been an entry and exit point for the United States since before the Louisiana Purchase.

From New York Times • Jan. 20, 2023

As for the constitutional question, he regarded federal jurisdiction over the western territories as a clear precedent that had been established, irony of ironies, by Jefferson’s executive action in the Louisiana Purchase.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis