Oklahoma (; Pawnee: Uukuhuúwa, Cayuga: Gahnawiyoˀgeh) is a state in the South Central region of the United States. It is the 20th-most extensive and the 28th-most populous of the fifty United States. The state's name is derived from the Choctaw words okla and humma, meaning "red people". It is also known informally by its nickname, "The Sooner State", in reference to the non-Native settlers who staked their claims on land before the official opening date of lands in the western Oklahoma Territory or before the Indian Appropriations Act of 1889, which dramatically increased European-American settlement in the eastern Indian Territory. Oklahoma Territory and Indian Territory were merged into the State of Oklahoma when it became the 46th state to enter the union on November 16, 1907. Its residents are known as Oklahomans, or informally as Okies, and its capital and largest city is Oklahoma City.
A major producer of natural gas, oil, and agricultural products, Oklahoma relies on an economic base of aviation, energy, telecommunications, and biotechnology. Both Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly two thirds of Oklahomans living within their metropolitan statistical areas.
With small mountain ranges, prairie, mesas, and eastern forests, most of Oklahoma lies in the Great Plains, Cross Timbers, and the U.S. Interior Highlands, a region prone mainly to severe weather. In addition to having a prevalence of English, German, Scottish, Scots-Irish, African American, and Native American ancestry, more than 25 Native American languages are spoken in Oklahoma, ranking third behind Alaska and California.
Oklahoma is on a confluence of three major American cultural regions and historically served as a route for cattle drives, a destination for Southern settlers, and a government-sanctioned territory for Native Americans.