Thomas Jefferson, the third president of the United States, and François Barbé-Marbois, the representative of France at the negotiations, agreed amicably in 1803 that the territory of Colonial French Louisiana is comprised of all tributaries of the Missouri as well as those of the Mississippi on its western shores.
Although most rivers and streams in the southern part of these Canadian provinces run towards Hudson Bay, the Milk River in Alberta and the Poplar River and Big Muddy Creek in Saskatchewan flow southward to the Gulf of Mexico through the Missouri and the mighty Mississippi. The lands drained by these tributaries were therefore considered an integral part of Colonial French Louisiana. In 1803, there were no settled colonies in the Canadian part of French Louisiana. Fort La Jonquière (now Calgary) was situated further north.
In the 1818 London Convention between Great Britain and the United States regarding the North American boundary it was decided that the 49th parallel, from Lake of the Woods to the Rocky Mountains, would separate the United States from its northern neighbor, a point on which both countries already had agreed in 1807.