| Butel Municipality | 0 | Republic of North Macedonia | MK-09 |
| BV | 0 | Romania | RO-BV |
| BW | 0 | Germany | DE-BW |
| BY | 0 | Germany | DE-BY |
| BZ | 0 | Romania | RO-BZ |
| BZ | 0 | Hungary | HU-BZ |
| C | 0 | Ireland | IE-C |
| CA | 0 | Moldova | MD-CA |
| CA | 0 | Luxembourg | LU-CA |
| CA | 8.25 | United States | US-CA |
| Čair Municipality | 0 | Republic of North Macedonia | MK-79 |
| Calabria | 0 | Italy | IT-78 |
| CAM | 0 | United Kingdom | GB-CAM |
| Campania | 0 | Italy | IT-72 |
| Canillo | 0 | Andorra | AD-02 |
| Cankova Municipality | 0 | Slovenia | SI-152 |
| Canton 10 | 0 | Bosnia and Herzegovina | BA-10 |
| Capital Region | 0 | Iceland | IS-1 |
| Capital Region of Denmark | 0 | Denmark | DK-84 |
| Carinthia | 0 | Austria | AT-2 |
| Carnikava Municipality | 0 | Latvia | LV-020 |
| Čaška Municipality | 0 | Republic of North Macedonia | MK-80 |
| Castelo Branco | 0 | Portugal | PT-05 |
| CAY | 0 | United Kingdom | GB-CAY |
| CB | 0 | Spain | ES-CB |
| CBF | 0 | United Kingdom | GB-CBF |
| CCG | 0 | United Kingdom | GB-CCG |
| CE | 0 | Russia | RU-CE |
| CE | 0 | Spain | ES-CE |
| CE | 0 | Ireland | IE-CE |
| Centar Municipality | 0 | Republic of North Macedonia | MK-77 |
| Centar Župa Municipality | 0 | Republic of North Macedonia | MK-78 |
| Central Banat District | 0 | Serbia | RS-02 |
| Central Bosnia Canton | 0 | Bosnia and Herzegovina | BA-06 |
| Central Denmark Region | 0 | Denmark | DK-82 |
| Central Finland | 0 | Finland | FI-08 |
| Central Greece Region | 0 | Greece | GR-H |
| Central Macedonia | 0 | Greece | GR-B |
| Central Ostrobothnia | 0 | Finland | FI-07 |
| Centre-Val de Loire | 0 | France | FR-CVL |
| Cerklje na Gorenjskem Municipality | 0 | Slovenia | SI-012 |
| Cerknica Municipality | 0 | Slovenia | SI-013 |
| Cerkno Municipality | 0 | Slovenia | SI-014 |
| Cerkvenjak Municipality | 0 | Slovenia | SI-153 |
| Češinovo-Obleševo Municipality | 0 | Republic of North Macedonia | MK-81 |
| Cēsis Municipality | 0 | Latvia | LV-022 |
| Česká Lípa | 0 | Czech Republic | CZ-511 |
| České Budějovice | 0 | Czech Republic | CZ-311 |
| Český Krumlov | 0 | Czech Republic | CZ-312 |
| Cesvaine Municipality | 0 | Latvia | LV-021 |
| CGN | 0 | United Kingdom | GB-CGN |
| CGV | 0 | United Kingdom | GB-CGV |
| Champagne-Ardenne | 0 | France | FR-G |
| Chania Regional Unit | 0 | Greece | GR-94 |
| CHE | 0 | United Kingdom | GB-CHE |
| CHE | 0 | Russia | RU-CHE |
| Cheb | 0 | Czech Republic | CZ-411 |
| Cherkasy Oblast | 0 | Ukraine | UA-71 |
| Chernihiv Oblast | 0 | Ukraine | UA-74 |
| Chernivtsi Oblast | 0 | Ukraine | UA-77 |
| Chiesanuova | 0 | San Marino | SM-02 |
| Chomutov | 0 | Czech Republic | CZ-422 |
| Chrudim | 0 | Czech Republic | CZ-531 |
| CHU | 0 | Russia | RU-CHU |
| CHW | 0 | United Kingdom | GB-CHW |
| Cibla Municipality | 0 | Latvia | LV-023 |
| City Municipality of Celje | 0 | Slovenia | SI-011 |
| City Municipality of Novo Mesto | 0 | Slovenia | SI-085 |
| CJ | 0 | Romania | RO-CJ |
| CKF | 0 | United Kingdom | GB-CKF |
| CKT | 0 | United Kingdom | GB-CKT |
| CL | 0 | Romania | RO-CL |
| CL | 0 | Moldova | MD-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Luxembourg | LU-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Monaco | MC-CL |
| CL | 0 | Spain | ES-CL |
| CL | 0 | Monaco | MC-CL |
| CLD | 0 | United Kingdom | GB-CLD |
| CLK | 0 | United Kingdom | GB-CLK |
| CLR | 0 | United Kingdom | GB-CLR |
| CM | 0 | Moldova | MD-CM |
| CM | 0 | Spain | ES-CM |
| CMA | 0 | United Kingdom | GB-CMA |
| CMD | 0 | United Kingdom | GB-CMD |
| CMN | 0 | United Kingdom | GB-CMN |
| CN | 0 | Spain | ES-CN |
| CN | 0 | Ireland | IE-CN |
| CO | 0 | Monaco | MC-CO |
| CO | 2.9 | United States | US-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
