Population totals for Colorado, counties & places, 1870 to 2010 are available here.
Historical Census data can also be obtained through the National Historical Geographic Information System. This site presents data for the people and the economy of the U.S. for each state and county from 1790 to 1960.
Population estimates are produced annually by the State Demography Office. The most recent estimate available is for the year of 2018 and was finalized in September of 2019.
This option allows the user to select any combination of state, counties or municipalities for the year 2010 to current.
The County Profile database allows the user to select population estimates along with other variables, for years 1985 to present.
Population forecasts are produced annually by the State Demography Office.
These tables illustrate the population for future years, based on plausible courses of future population change (see Forecasts Methodology for more information.) The forecasts for the State of Colorado & Sub-state regions are available for the years 2000 to 2050.