Wichita is the largest city in the U.S. state of Kansas. As of the 2000 United States Census, it had a population of 344,284, growing to an estimated 372,186 by 2009. Located in south-central Kansas on the Arkansas River, Wichita is the county seat of Sedgwick County and the principal city of the Wichita metropolitan area. As of 2009, the metro area had an estimated population of 612,683. The city was incorporated in 1870, based on the success of businessmen who came to hunt and trade with native populations. Its position on the Chisholm Trail made it a destination for cattle drives heading north to access railroads to eastern markets. In the 20th century, aircraft pioneers such as Clyde Cessna, Walter Beech and Bill Lear began projects that would lead to Wichita's nicknaming as the Air Capital of the World.