<P> The geographical limits of Upper Louisiana were never precisely defined, but the term gradually came to describe the country southwest of the Great Lakes and, in some cases, crossing the Mississippi River into present - day Missouri . A royal ordinance of 1722 may have featured the broadest definition: all land claimed by France south of the Great Lakes and north of the mouth of the Ohio River, which would include the lower Missouri Valley as well as both banks of the Mississippi . </P> <P> A generation later, trade conflicts between Canada and Louisiana led to a defined boundary between the French colonies; in 1745, Louisiana governor general Vaudreuil set the northern and eastern bounds of his domain as the Wabash valley up to the mouth of the Vermilion River (near present - day Danville, Illinois); from there, northwest to le Rocher on the Illinois River, and from there west to the mouth of the Rock River (at present - day Rock Island, Illinois). Thus, Vincennes and Peoria were the limit of Louisiana's reach . The outposts at Ouiatenon (on the upper Wabash near present - day Lafayette, Indiana), Chicago, Fort Miamis (near present - day Fort Wayne, Indiana), and Prairie du Chien operated as dependencies of Canada . </P> <P> This boundary remained in effect through the capitulation of French forces in Canada in 1760 until the Treaty of Paris in 1763, after which France surrendered its remaining territory east of the Mississippi to Great Britain . (Although British forces had occupied the "Canadian" posts in the Illinois and Wabash countries in 1761, they did not occupy Vincennes or the Mississippi River settlements at Cahokia and Kaskaskia until 1764, after the ratification of the peace treaty .) As part of a general report on conditions in the newly conquered Province of Canada, Gen. Thomas Gage (then commandant at Montreal) explained in 1762 that, although the boundary between Louisiana and Canada wasn't exact, it was understood the upper Mississippi (above the mouth of the Illinois) was in Canadian trading territory . </P> <P> Following the transfer of power--at which time many of the French settlers on the east bank of the Mississippi crossed the river to what had become Spanish Louisiana--the eastern Illinois Country became part of the British Province of Quebec, and later the United States' Northwest Territory . Those fleeing British control founded outposts such as the important settlement of St. Louis (1764). This became a French fur - trading center, connected to trading posts on the Missouri and Upper Mississippi rivers, leading to later French settlement in that area . </P>

The french governor founded the city of at the mouth of the mississippi river