sentences:  The eyes of the colonists therefore turned to the new United States, both as a source of supplies and an (illegal) outlet for their furs.The rich fur areas along the upper Mississippi, Minnesota, Des Moines, and Missouri Rivers, otherwise occupied by peoples of the First Nations, were exploited by independent fur traders operating from Prairie du Chien, Wisconsin in the late eighteenth century.At the beginning of the nineteenth century, these traders established fur posts in the Minnesota River valley at Lake Traverse, Big Stone Lake, Lac qui Parle, and Traverse des Sioux.