In 1803 the US bought the area of the US known as the Louisiana Territory from which country?

It became known as the "Louisiana Purchase" and stretched from the mouth of the Mississippi River to Canada, including what later became the states of Oklahoma, Arkansas, Kansas, Missouri, Iowa, Nebraska, South Dakota, and parts of what became Louisiana, Texas, Colorado, Wyoming, Montana, Minnesota and New Mexico, as well as the provinces of Alberta and Saskatchewan, after additional purchases, cessions and treaties.