In 1800 Spain gave Louisiana to France, but not without first closing her ports to us.
Napoleon had wanted a Caribbean Empire, by his plan was foiled by the Haitian Revolution of 1800. His attack on Haiti had failed, by 1800 they had become a Black Republic and Napoleon has his sights on the Caribbean Jewel. He sent 90,000 soldiers to retake Haiti and the majority of them died from Yellow Fever. At this point, due to the failure, Haiti became unreachable and Louisiana became useless to Napoleon.
In 1802 U.S. access to New Orleans was revoked and a series of representatives were sent to negotiate for the port’s purchase. They got more than they bargained for when Napoleon, in his great need for the cash, offered Louisiana to Jefferson for 15 million dollars, a mere 13¢ an acre and Jefferson was forced to purchase the land on his own authority going against his stated views of government; he didn't think he had the executive power to make the purchase, but the deal was too good to pass up and it doubled the size of the country which was good for Jefferson’s agrarian ideas.