State of Colorado
Population: 5,029,196 (2010 U.S. Census)
Open or Concealed: Concealed
May issue or Shall issue: Shall Issue
Administrative Body: Colorado Bureau of Investigation
Reciprocity with: Alabama, Alaska, Arizona, Arkansas, Delaware, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Mexico, North Carolina, North Dakota, OhioOklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia,  Wisconsin, and Wyoming
Special Note:
Pursuant to Colorado law (CRS 18-12-213), the State of Colorado will recognize a valid permit issued in another state IF the permit was issued to a resident of the state issuing the permit, and the permit tee is 21 years of age or older, and the other state recognizes Colorado permits as valid in their state. Hence, a "yes" indicates that a valid Colorado permit is recognized in that state, subject to their laws. When traveling with a Colorado permit, it is advisable to contact the state you are visiting to confirm reciprocity and to review that state's firearms laws.
The state of Colorado no longer recognizes the validity of any permit issued by any state to a nonresident of that state
Link to The State of Colorado