The Hi-Line is a geographical term referring to the portion of the northern United States south of the Canada–United States border along which runs the main line of the BNSF Railway (originally the mainline of the Great Northern Railway) and U.S. Highway 2. Specifically, the term most commonly refers to northern Montana, but can also mean the entire region between Spokane, Washington and Minnesota, or even the entire Seattle to Minneapolis route of the BNSF railway.
Shelby, Montana is generally considered the central town along the Hi-Line, and the Hi-Line name has its origins in the railroad line being the northernmost railway line in the region. The stretch of the route between Havre and Whitefish, Montana is sometimes referred to as the Hi-Line Subdivision.