Northern Commonwealth

The Northern Commonwealth was one of the thirteen commonwealths of the pre-War United States. Created in the early 21st century, it was comprised of the former states of Montana, Wyoming, North Dakota and South Dakota.

Wyoming Wasteland
In 2281, the Great Khans could have abandoned the Mojave, and worked with the Followers of the Apocalypse in Wyoming to create a mighty empire. Also, the White Legs can flee to Wyoming after their leader, Salt-Upon-Wounds, is killed.

The region is described as a vast wilderness, and it experiences harsh winters.

Montana Wasteland
Little is known about this area, except that there is a Brotherhood of Steel bunker here, the Lonesome Drifter was born here, there are coal mines active in the area and, if the Courier has the Lady Killer perk, it is revealed he may have had a child with a woman from there.

Montana Wasteland

 * Montana bunker (Mentioned in Fallout 3)

South Dakota Wasteland

 * Mount Rushmore (Mentioned in Fallout 4)

Appearances
The Northern Commonwealth is mentioned only in Fallout 3, and Fallout: New Vegas and its add-on Honest Hearts. South Dakota's Mount Rushmore appears in the Atomic Command game in Fallout 4.