Oklahoma is a state in the South Central and Southern Plains region of the United States, bordered by the state of Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New Mexico on the west, and Colorado on the northwest. Partially in the western extreme of the Upland South, it is the 20th-most extensive and the 28th-most populous of the 50 United States. Its residents are known as Oklahomans, and its capital and largest city is Oklahoma City.
The state's name is derived from the Choctaw words okla, "people" and humma, which translates as "red" or "honored." Oklahoma is also known informally by its nickname, "The Sooner State", in reference to the colonizers 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 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.