Admitted to the Union on November 16, 1907 as the 46th state. Prior to statehood, existed as Indian Territory (1834 – 1907) and Oklahoma Territory (1890 – 1907).

• 1820 federal censuses for Missouri and Arkansas Territories that covered present-day Oklahoma lost.
• No federal censuses were taken 1830 – 1850 in present-day Oklahoma.
• 1860 federal census extant for non-Indians, the list appearing after the 1860 census for Yell County, Arkansas.
• 1870 no federal census available.
• 1880 – 1890 federal censuses lost.
• 1890 Union Veterans and Widows census extant.
• 1900 – 1940 federal censuses extant for all counties.