The Ozarks is part of the Interior Highlands region of North America, the only extensive mountainous and hilly stretch of land between the Appalachians and the Rockies. It is comprised of more than 40,000 square miles, or roughly the size of the state of Ohio. The area covered by the Ozarks, which consists of at least nine geographical subregions of varying topography and soil types, includes most of the southern half of Missouri, much of northern Arkansas, a section of northeastern Oklahoma, and a corner of southwestern Kansas. Though the terrain of the Ozarks stretches to the outskirts of St. Louis, in comparison with most of the United States east of the Rockies the Ozarks is a very rural and sparsely populated region. The region does, however, contain two thriving metropolitan areas. Springfield, in southwest Missouri, is the region’s largest city and has long been known as the “Queen City of the Ozarks.” In northwestern Arkansas the cities of Fayetteville, Springdale, Rogers, and Bentonville have in recent years grown to create a second Ozarks metropolitan district.