Economic ties have spanned the contemporary border between Washington State and Canada for as long as the Pacific Northwest has been inhabited. The native peoples of North America interacted across the border for centuries prior to the arrival of European explorers. In the early 19th century, the major regional European economic entity was the Hudson’s Bay Company. The fur-trading operations of this British-chartered corporation took place throughout its “Columbia Department” (a region that straddled the modern Canada – U.S. border), with outposts at locations such as Fort Vancouver and Fort Nisqually. The contemporary border dates from 1846, when the 49th parallel was established as the boundary between the British and the American portions of the Columbia Department.
Storer, Paul; Davidson, David L.; and Trautman, Laurie, "Washington State's Economy in Relation to Canada and the Border" (2015). Border Policy Research Institute Publications. 92.