The Ozarks (also referred to as Ozarks Mountain Country, the Ozark Mountains or the Ozark Plateau) are a physiographic, geologic, and cultural highland region of the central United States. It covers much of the south half of Missouri and an extensive portion of northwest and North central Arkansas. The region also extends westward into northeast Oklahoma and extreme southeast Kansas. Although sometimes referred to as the Ozark Mountains, the region is actually a high and deeply dissected plateau. Geologically, the area is a broad dome around the Saint Francois Mountains.
The Ozark Highlands area, covering nearly 47,000 square miles (122,000 km2), is by far the most extensive mountainous region between the Appalachians and the Rocky Mountains. Together, the Ozarks and Ouachita Mountains form an area known as the U.S. Interior Highlands, and are sometimes referred to collectively. For example, the ecoregion called Ozark Mountain Forests includes the Ouachita Mountains, although the Arkansas River valley and the Ouachitas, both south of the Boston Mountains, are not usually considered part of the Ozarks.