By the 1783 Treaty of Paris, the border between New Spain and American territory ran along the Mississippi. In 1795, the United States secured unfettered navigation rights for the Mississippi from the Spanish government. However, in 1802, the US learnt that the French Emperor, Napoleon, then dominating Europe, was about to force the Spanish king to surrender Louisiana. The prospect of a powerful France controlling its western border alarmed the US government, who sent Secretary of State Monroe to Paris to negotiate. Circumstances worked to the US advantage. An adverse turn in the Haitian revolt and a fresh British declaration of war on France, persuaded Napoleon to sell Louisiana to the US for $15 million in July 1803. In 1812, the new possessions, which encompassed 530 million acres, were renamed the Missouri Territory and, in 1819, the Adams-Onis Treaty conceded the land west of the Sabine River to Spain in exchange for Florida.
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