Known to locals as "The Bob," this wilderness area joins others to form a 1.5 million acre section of protected forest accessible only by trail. The Seeley Swan Valley abuts its western flank and the The Continental Divide runs through the middle of the wilderness.
Bob Marshall was a forester, author, explorer and leader in the protection of wild lands throughout America. Before Marshall's death at the age of 39 of ill health, he spent days, weeks and months hiking the unmapped country known as the South Fork of the Flathead River. By the late 1930s, he had laid out initial plans for the designation of the Wilderness area, which included three separate primitive areas: South Fork, Sun River and Pentagon.
In 1940, shortly after he died, the U.S. Secretary of Agriculture designated 950,000 acres of wilderness.
In 1964, The Wilderness Act was passed by Congress and the Bob Marshall Wilderness received statutory wilderness protection as a part of the National Wilderness Preservation System.