Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,579,212 residents in 2006 and a land area of 68,667 square miles (177,847 km²), Oklahoma is the 28th most populous and 20th-largest state. Its name is derived from the Choctaw words okla and humma, meaning "land of the red man", and is known informally by its nickname, The Sooner State. Formed from Indian Territory on November 16, 1907, Oklahoma was the 46th state to enter the union. Its citizens are known as Oklahomans, and the state's capital and largest city is Oklahoma City.

A major producer of natural gas, oil and food, Oklahoma relies on an economic base of aviation, energy, telecommunications, and biotechnology. It has one of the fastest growing economies in the nation, ranking third in per capita income growth and leading in gross domestic product growth. Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly 60 percent of Oklahomans living in their metropolitan statistical areas. The state holds a mixed record in education and healthcare, and its largest universities participate in the NCAA and NAIA athletic associations, while two house athletic departments rated among the most successful in American history.

With small mountain ranges, prairie, and eastern forests, most of Oklahoma lies in the Great Plains and the U.S. Interior Highlands—a region especially prone to severe weather. With a prevalence of German, Irish, British and Native American ancestry, more than 25 Native American languages are spoken in Oklahoma, the most of any state. It is located 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. Part of the Bible Belt, widespread belief in evangelical Christianity makes it one of the most politically conservative states, though voter registration is largest in the Democratic Party.