| | | Cherokee County | OK | 40021 | | Tahlequah, OK 45140 | | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=CherokeeCounty+OK |
| | | Choctaw County | OK | 40023 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=ChoctawCounty+OK |
| | | Cimarron County | OK | 40025 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=CimarronCounty+OK |
| | | Cleveland County | OK | 40027 | | Oklahoma City, OK 36420 | Oklahoma City-Shawnee, OK 416 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=ClevelandCounty+OK |
| | | Coal County | OK | 40029 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=CoalCounty+OK |
| | | Comanche County | OK | 40031 | | Lawton, OK 30020 | Lawton-Duncan, OK 334 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=ComancheCounty+OK |
| | | Cotton County | OK | 40033 | | Lawton, OK 30020 | Lawton-Duncan, OK 334 | Outlying | metro county (urban) | farm-dependent | https://maps.google.com/?q=CottonCounty+OK |
| | | Craig County | OK | 40035 | | | | | nonmetro county (rural) | federal/state
government-dependent | https://maps.google.com/?q=CraigCounty+OK |
| | | Creek County | OK | 40037 | | Tulsa, OK 46140 | Tulsa-Bartlesville-Muskogee,
OK 538 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=CreekCounty+OK |
| | | Custer County | OK | 40039 | | Weatherford, OK 48220 | Weatherford-Elk City, OK 555 | Central | nonmetro county (rural) | mining-dependent | https://maps.google.com/?q=CusterCounty+OK |
