| | Crowley County | CO | 08025 | | | | | nonmetro county (rural) | federal/state
government-dependent | https://maps.google.com/?q=CrowleyCounty+CO |
| | Costilla County | CO | 08023 | | Alamosa, CO 10480 | | Outlying | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=CostillaCounty+CO |
| | Conejos County | CO | 08021 | | Alamosa, CO 10480 | | Outlying | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=ConejosCounty+CO |
| | Clear Creek County | CO | 08019 | | Denver-Aurora-Centennial,
CO 19740 | Denver-Aurora-Greeley, CO 216 | Outlying | metro county (urban) | mining-dependent | https://maps.google.com/?q=ClearCreekCounty+CO |
| | Cheyenne County | CO | 08017 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=CheyenneCounty+CO |
| | Chaffee County | CO | 08015 | | | | | nonmetro county (rural) | recreation | https://maps.google.com/?q=ChaffeeCounty+CO |
| | Broomfield County | CO | 08014 | | Denver-Aurora-Centennial,
CO 19740 | Denver-Aurora-Greeley, CO 216 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=BroomfieldCounty+CO |
| | Boulder County | CO | 08013 | | Boulder, CO 14500 | Denver-Aurora-Greeley, CO 216 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=BoulderCounty+CO |
| | Bent County | CO | 08011 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=BentCounty+CO |
| | Baca County | CO | 08009 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=BacaCounty+CO |