Gaining control of Florida for the United States would mean gaining control of the Mississippi River. That was an important route for trade. At the same time, Britain also wanted to regain control of Florida. Finally in 1821, the United States was successful in purchasing Florida from Spain.
Florida had become a burden to Spain, which could not afford to send settlers or garrisons, so the Spanish government decided to cede the territory to the United States in exchange for settling the boundary dispute along the Sabine River in Spanish Texas.
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