The U.S. Interior Highlands, commonly called Interior Highlands is a mountainous region in the Central United States spanning northern and western Arkansas, southern Missouri, eastern Oklahoma, and extreme southeastern Kansas.

The name is designated by the United States Geological Survey to refer to the combined subregions of the Ouachita Mountains and the Ozark Plateaus. The Interior Highlands is one of the very few mountainous regions between the Appalachians and Rockies.

Geologically, the area is a broad dome with the exposed core in the St. Francois Mountains. The Interior Highlands cover nearly 47,000 miles (76,000 km), making it the most extensive highland region between the Appalachians and Rockies.

The Ouachita Mountains, commonly referred to as the Ouachitas are a mountain range located in western Arkansas and southeastern Oklahoma.

In the very southeast of the range, the Ouachitas continue in the subsurface to make a poorly understood connection with the Appalachians. To the southwest, the Ouachitas join with the Marathon area in west Texas.

The highest natural point in the Quachitas is Mount Magazine in the Frontal Quachita Mountains, that rises to an elevation of 2753 feet.

Subranges to the Ouachitas include: 1. Athens Piedmont, 2. Caaddo, Cossatot, Missouri Mountains, 3. Cross Mountains, 4. Crystal Mountains, 5. Fourche Mountains, 6. Frontal Ouachita Mountain, 7. Trap Mountains, and 8. Zig Zag Mountains.

Two mountain ranges are found within the Ozark Mountains: the Boston Mountains of Arkansas and the Saint Francois Mountains of Missouri.

The highest point of the Ozark Mountains is Buffalo Lookout (2,561 feet) found in the Boston Mountains.