26. Mountains Make Good Borders

In the vast expanse west of the Mississippi River, most contiguous U.S. state borders are characterized by straight lines or follow natural features like rivers. However, there’s one notable exception: the border between Idaho and Montana, specifically along the Bitterroot Mountain Range.

This boundary doesn’t adhere to the common pattern of straight lines or river courses, but instead, it traverses the rugged terrain of the Bitterroots, meandering along the mountain crests. This unique deviation from the norm adds to the mystique of the Western landscape, showcasing the challenges and intricacies involved in defining state borders.