Arkansas is a state located in the Southern region of the United States. Its name is an Algonquian name of the QuapawIndians. The state's diverse geography ranges from the mountainous regions of the Ozarks and the Ouachita Mountains, which make up the U.S. Interior Highlands, to the eastern lowlands along the Mississippi River and the Arkansas Delta. Arkansas is the 29th most extensive and the 32nd most populous of the 50 United States. The capital and most populous city is Little Rock, located in the central portion of the state. The Territory of Arkansas was admitted to the Union as the 25th state on June 15, 1836.