A landlocked state, Arkansas rises from lowlands along the Mississippi River in the east to the Ozark Mountains in the north. The Quapaw, Osage, and Caddo peoples inhabited the area until white settlement began in large numbers, after the 1803 Louisiana Purchase. Arkansas achieved statehood June 15, 1836, seceded to join the Confederacy in 1861, and was readmitted in 1868. The state's chief industries are manufacturing, especially processed food and chemicals. It is the largest poultry-producing state, and the only state with an active diamond mine. President Bill Clinton (1993-2001) is a native of Arkansas.