United States completes the Louisiana Purchase
- Date
- 30 April 1803
- Category
- Politics & governance
- Region
- North America (Mississippi Valley & Great Plains)
- Era
- Modern
- Significance
By a treaty signed in Paris and dated 30 April 1803, the United States bought the vast Louisiana Territory from Napoleonic France for roughly $15 million, acquiring some 828,000 square miles of land west of the Mississippi River.
Negotiated by Robert Livingston and James Monroe with François Barbé-Marbois, the purchase roughly doubled the size of the young republic and secured American control of the Mississippi and the port of New Orleans. France, having lost Saint-Domingue and facing renewed war in Europe, abandoned its ambitions for a North American empire. President Thomas Jefferson, despite constitutional doubts about the executive's authority to acquire territory, pressed the deal through; the Senate ratified it on 20 October 1803. The acquisition opened immense lands to settlement and exploration, prompting the Lewis and Clark expedition, but it also accelerated the dispossession of Native nations and intensified sectional conflict over whether slavery would expand into the new territories. It stands as a foundational moment in United States continental expansion.
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Empires active in 30 April 1803
- British Empire1583 CE – 1997 CE
- Russian Empire1721 CE – 1917 CE
- Qing Dynasty1636 CE – 1912 CE
- Spanish Empire1492 CE – 1976 CE
- Portuguese Empire1415 CE – 1999 CE
- Mughal Empire1526 CE – 1857 CE
Related politics & governance events
- Britain abolishes the transatlantic slave trade25 March 1807
- Congress of Vienna and the Concert of EuropeSeptember 1814 – June 1815
- The Slavery Abolition Act ends slavery across the British Empire28 August 1833 (in force 1 August 1834)
- The Revolutions of 1848 (the Springtime of Peoples)1848–1849
- Commodore Perry forces the opening of Japan1853–1854 (Treaty of Kanagawa, 31 March 1854)
- Indian Rebellion of 1857 and the birth of the British Raj1857–1858 (rebellion); Government of India Act 2 August 1858
Further reading
The wider story
Empire of the Summer Moon
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