It is named after Bob Marshall (1901–1939), an early forester in the federal government, conservationist, and co-founder of The Wilderness Society.

Formally designated in 1964, the Bob Marshall Wilderness extends for 60 miles (97 km) along the Continental Divide and consists of 1,009,356 acres (4,084.72 km2).

[2] The five ranger districts administering "The Bob" manage 1,856 miles (2,987 km) of trail that are open to foot and stock use only.

[1] A long escarpment known as the Chinese Wall averages 1,000 feet (300 m) high from its base and extends for 22 miles (35 km).

[3] The Bob is also home to many other large mammals, such as moose, elk, black bear, mountain goat, bighorn sheep, wolverine, cougar, Canadian lynx, and wolf.

The wilderness was administratively created in 1940 from the South Fork, Pentagon, and Sun River Primitive Areas (which were designated in the 1930s).