North Texas was the traditional home of several tribes of Plains Indians, notably the Kiowa and Comanche. The first white settlers arrived in 1879, Wichita County was organized in 1882, and the railroad arrived the same year. Agriculture dominated the economy until early in the 20th century when oil was discovered in the area. This discovery led to an oil boom that peaked during World War I. For the next several years, Wichita Falls flourished as a refinery town while continuing to support the agricultural economy that was based largely on cattle and wheat. During World War II, Sheppard Air Force Base was established in Wichita Falls and is still an important contributor to the economy. The refineries have long since disappeared, but oil production and farming remain. Also important is Midwestern State University with a student body numbering approximately 6,000.