Oklahoma is a state located in the South Central region of the United States of America. Oklahoma is the 20th most extensive and the 28th most populous of the 50 United States. The state's name is derived from the Choctaw words okla and humma, meaning "red people", and is known informally by its nickname, The Sooner State. Formed by the combination of Oklahoma Territory and Indian Territory on November 16, 1907, Oklahoma was the 46th state to enter the union. Its residents are known as Oklahomans or, informally "Okies", and its capital and largest city is Oklahoma City. A major producer of natural gas, oil, and agriculture, Oklahoma relies on an economic base of aviation, energy, telecommunications, and biotechnology. It has one of the fastest growing economies in the nation, ranking among the top states in per capita income growth and gross domestic product growth. Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly 60 percent of Oklahoman's living in their metropolitan statistical areas.