All recorded cultural resources receive a Smithsonian number. This is a trinomial number with a state numerical designation (Colorado is #5), a two letter designation for the county, and a sequential number for the resource.  For example, the first recorded site in Rio Blanco county is 5RB1.  Site numbers are assigned by writing the OAHP office or calling 303-866-5216.  Do not assign a new site number to previously recorded sites with existing site numbers.  Please contact the OAHP staff to determine the correct site number if a structure has been moved or if new construction connects two previously separate properties.