How the territory of Louisiana and Oregon became a territory of the United States

   Originally Spain, Great Britain, Russia, and the United States claimed the territory. In 1819, under terms of the Transcontinental Treaty, Spain ceded its claims to the territory to the United States.

Explanation:

The Louisiana Purchase (French: Vente de la Louisiane 'Sale of Louisiana') was the acquisition of the territory of Louisiana by the United States from France in 1803. In return for fifteen million dollars, or approximately eighteen dollars per square mile, the United States nominally acquired a total of 828,000 sq mi (2,140,000 km 2; 530,000,000 acres).

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