| Code | Name | Region |
|---|---|---|
| USCE7 | Colchester | CT |
| USDGI | Colchester | IL |
| USCCV | Colchester | VT |
| USC9R | Colcord | OK |
| USCDB | Cold Bay | AK |
| USFCG | Cold Spring | KY |
| USCDM | Cold Spring | MN |
| USLPM | Cold Spring | NY |
| USHQ2 | Cold Spring Harbor | NY |
| USCOI | Cocoa | FL |
| USC2B | Cocoa Beach | FL |
| US6CC | Cocolalla | ID |
| USCCU | Coconut Creek | FL |
| USNVV | Coconut Grove | FL |
| USC2N | Coden | AL |
| USC6S | Codorus | PA |
| USZUO | Codorus Furnance | PA |
| USCOD | Cody | WY |
| USC7E | Coeburn | VA |
| USCOE | Coeur D'alene | ID |
| USOYF | Coeymans | NY |
| USCFA | Coffee Point | AK |
| USC5N | Coffeen | IL |
| US9FE | Coffeeville | MS |
| USCFV | Coffeyville | KS |
| USKCC | Coffman Cove | AK |
| US5CF | Cofield | NC |
| USCG8 | Cogan Station | PA |
| USKOA | Coggon | IA |
| USTTC | Coaltown | PA |
| USVTJ | Coalville | UT |
| USCG7 | Coarsegold | CA |
| USCS7 | Coatesville | IN |
| USCTH | Coatesville | PA |
| USVOS | Coats | NC |
| USC5B | Cobb | CA |
| USOBB | Cobb | WI |
| USCK2 | Cobbs Creek | VA |
| US5CD | Cobden | IL |
| USS2K | Cobleskill | NY |
| USCUR | Coburg | OR |
| USQOH | Cochecton | NY |
| USC55 | Cochise | AZ |
| USOHN | Cochran | GA |
| USRAW | Cochrane | WI |
| USCOJ | Cochranton | PA |
| USC9N | Cochranville | PA |
| USCCQ | Cockeysville | MD |
| USCK9 | Cockrell Hill | TX |
| USCYW | Clyattville | GA |