Admitted to the Union on August 1, 1876 as the 38th state. Prior to statehood, in the 1860 census what is now present-day Colorado lay in four territorial jurisdictions, three of which are extant: Kansas Territory, Nebraska Territory, and New Mexico Territory. The Colorado area of Utah Territory was unsettled by whites and was not enumerated in 1860. Since there are numerous Park/e/s listings in both Kansas and Nebraska Territories in 1860, those will be included here.

• 1870—1940 federal censuses extant for all counties except for 1890.
• 1885 state census extant for all counties except Fremont and Garfield.