What mountain range in western Arkansas is the only major U.S. mountain range that runs east to west?

The Ouachita Mountains are unique among major U.S. mountain ranges because they run in an east-west direction, unlike most other mountain ranges in the country, which typically extend north to south. This distinct orientation is due to the geological processes that shaped the region, including the folding and faulting of the earth's crust. This east-west alignment of the Ouachita Mountains contrasts sharply with other well-known mountain ranges, such as the Appalachian Mountains and the Rocky Mountains, which are aligned north-south. The Ozark Mountains, while located in the same general area, do not share this specific orientation and primarily run north to south.