Montana State Highway 37 (MT 37) is a state highway in the US state of Montana. It begins in downtown Libby, Montana at US 2 and takes a meandering course northeastwards upstream along the Kootenai River and the eastern shore of Lake Koocanusa before terminating at U.S. Route 93 at the northern end of Eureka, Montana. Previously, MT 37 also followed US 93 from Eureka into Whitefish and turned down what is now MT 40 towards US 2 and Glacier National Park until at least 1942.