Oklahoma (pronounce /ˌoʊkləˈhoʊmə/) 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.