Thomas Jefferson got it from France. Jefferson initially just wanted New Orleans in Louisiana. He offered France 10 million dollars for the territory. Napoleon gave up his plans for Louisiana and offered the entire Louisiana territory for 15 million dollars. Jefferson was conflicted about the decision since he worried that the Constitution did not give him the power for the President to purchase territory for the country. In the end, he decided to agree because of the public support and the growth the territory will give. And the territory doubled the size of the United States.