As of 2005 , Colorado has an estimated population of 4,665,177 , which is an increase of 63,356 , or 1.4 % , from the past year and an increase of 363,162 , or 8.4 % , since the year 2000 . As of 2005 , Colorado has an estimated population of 4,665,177 , which is an increase of 63,356 , or 1.4 % , from the prior year and an increase of 363,162 , or 8.4 % , since the year 2000 .