 In 1795 , the young United States and Spain signed <unk> 's Treaty , which recognized American rights to navigate the Mississippi River and store goods for export in New Orleans . Three years later , Spain revoked the treaty and in 1800 secretly returned Louisiana to Napoleonic France in the Third Treaty of San <unk> . This transfer was so secret that the Spanish continued to administer the territory . In 1801 , Spain restored rights to use the Mississippi and New Orleans to the United States . 
