The Arkansas Delta is one of the five natural regions of the state of Arkansas. It runs along the eastern border of the state next to the Mississippi River. It is part of the Mississippi River alluvial plain, itself part of the Mississippi embayment. The flat plain is bisected by Crowley's Ridge, a narrow band of rolling hills rising from 250 to 500 feet above the plain and on which many of the major cities and towns lie, including its largest — Jonesboro. Its eastern border runs concurrent with the Mississippi River down to the state's southernmost tip. Its lower western border follows the Arkansas river just outside Little Rock down through Pine Bluff where the border shifts to Bayou Bartholomew stretching south to the Arkansas-Louisiana state line. While the Arkansas Delta shares many geographic similarities with the Mississippi Delta, it is distinguished by its five unique sub-regions including the St. Francis Basin, Crowley's Ridge, the White River Lowlands, the Grand Prairie, and the Arkansas River Lowlands .The Arkansas Delta includes the entire counties of Arkansas, Chicot, Clay, Craighead, Crittenden, Cross, Desha, Drew, Greene, Lee, Mississippi, Monroe, Phillips, Poinsett, and St. Francis counties.[1] It also includes portions of Jackson, Prairie, Randolph, White, Pulaski, Lincoln, Jefferson, Lonoke and Woodruff counties.[