 Until 1818 the Red River Valley was considered British and was subject to several colonization schemes , such as the Red River Colony . The boundary where the Red River crossed the 49th parallel was not marked until 1823 , when Stephen H. Long conducted a survey expedition . When several hundred settlers abandoned the Red River Colony in the 1820s , they entered the United States by way of the Red River Valley , instead of moving to eastern Canada or returning to Europe . The region had been occupied by Métis people , the children of voyageurs and Native Americans , since the middle 17th century . 
