Tennessee is geographically diverse. It divides naturally into three “grand divisions”—upland, often mountainous, East Tennessee, Middle Tennessee with its foothills and basin, and the low plain of West Tennessee. These geographical “grand divisions” correspond to distinctive political and economic cultures of the state’s three regions. Travelers coming to the state from the east encounter first the lofty Unaka and Smoky Mountains, flanked on their western slope by the Great Valley of East Tennessee. Major cities and metropolitan areas in East Tennessee include the Tri-Cities in Northeast Tennessee, Knoxville, and Chattanooga on the southern border. Moving across the Valley floor, they next face the Cumberland Plateau, which historically attracted little settlement and presented a barrier to westward migration. West of the Plateau, one descends into the Central Basin of Middle Tennessee—a rolling, fertile countryside that drew hunters and settlers alike. The Central Basin is surrounded on all sides by the Highland Rim, the western ridge of which drops into the Tennessee River Valley. Nashville is the principal city of Middle Tennessee. Across the river begin the low hills and alluvial plain of West Tennessee. Memphis is the only major city in this predominantly agricultural region. Most information in this category is organized by county, city, or region.