| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Monaco | MC-CO |
| CO | 0 | Ireland | IE-CO |
| Coimbra | 0 | Portugal | PT-06 |
| CON | 0 | United Kingdom | GB-CON |
| Corfu Prefecture | 0 | Greece | GR-22 |
| Corinthia Regional Unit | 0 | Greece | GR-15 |
| Corsica | 0 | France | FR-COR |
| Cospicua | 0 | Malta | MT-06 |
| COV | 0 | United Kingdom | GB-COV |
| CR | 0 | Moldova | MD-CR |
| Črenšovci Municipality | 0 | Slovenia | SI-015 |
| Crete Region | 0 | Greece | GR-M |
| CRF | 0 | United Kingdom | GB-CRF |
| Črna na Koroškem Municipality | 0 | Slovenia | SI-016 |
| Črnomelj Municipality | 0 | Slovenia | SI-017 |
| CRY | 0 | United Kingdom | GB-CRY |
| CS | 0 | Romania | RO-CS |
| CS | 0 | Moldova | MD-CS |
| CS | 0 | Hungary | HU-CS |
| CSR | 0 | United Kingdom | GB-CSR |
| CT | 0 | Romania | RO-CT |
| CT | 0 | Moldova | MD-CT |
| CT | 6 | United States | US-CT |
| CT | 0 | Spain | ES-CT |
| CU | 0 | Moldova | MD-CU |
| CU | 0 | Russia | RU-CU |
| Čučer-Sandevo Municipality | 0 | Republic of North Macedonia | MK-82 |
| CV | 0 | Romania | RO-CV |
| CW | 0 | Ireland | IE-CW |
| CWY | 0 | United Kingdom | GB-CWY |
| D | 0 | Luxembourg | LU-D |
| D | 0 | Ireland | IE-D |
| DA | 0 | Russia | RU-DA |
| Dagda Municipality | 0 | Latvia | LV-024 |
| DAL | 0 | United Kingdom | GB-DAL |
| Dalarna County | 0 | Sweden | SE-W |
| Danilovgrad Municipality | 0 | Montenegro | ME-07 |
| Daugavpils | 0 | Latvia | LV-DGV |
| Daugavpils Municipality | 0 | Latvia | LV-025 |
| DB | 0 | Romania | RO-DB |
| DBY | 0 | United Kingdom | GB-DBY |
| DC | 5.75 | United States | US-DC |
| DE | 0 | United States | US-DE |
| DE | 0 | Hungary | HU-DE |
| Debarca Municipality | 0 | Republic of North Macedonia | MK-22 |
| Děčín | 0 | Czech Republic | CZ-421 |
| Delčevo Municipality | 0 | Republic of North Macedonia | MK-23 |
| Delvinë District | 0 | Albania | AL-DL |
| Demir Hisar Municipality | 0 | Republic of North Macedonia | MK-25 |
| Demir Kapija Municipality | 0 | Republic of North Macedonia | MK-24 |
| DEN | 0 | United Kingdom | GB-DEN |
| DER | 0 | United Kingdom | GB-DER |
| Destrnik Municipality | 0 | Slovenia | SI-018 |
| DEV | 0 | United Kingdom | GB-DEV |
| Devoll District | 0 | Albania | AL-DV |
| DGN | 0 | United Kingdom | GB-DGN |
| DGY | 0 | United Kingdom | GB-DGY |
| DI | 0 | Luxembourg | LU-DI |
| Dibër County | 0 | Albania | AL-09 |
| Dibër District | 0 | Albania | AL-DI |
| Dingli | 0 | Malta | MT-07 |
| Divača Municipality | 0 | Slovenia | SI-019 |
| DJ | 0 | Romania | RO-DJ |
| DL | 0 | Ireland | IE-DL |
| DNC | 0 | United Kingdom | GB-DNC |
| DND | 0 | United Kingdom | GB-DND |
| Dnipropetrovsk Oblast | 0 | Ukraine | UA-12 |
| DO | 0 | Moldova | MD-DO |
| Dobele Municipality | 0 | Latvia | LV-026 |
| Dobje Municipality | 0 | Slovenia | SI-154 |
| Dobrepolje Municipality | 0 | Slovenia | SI-020 |
| Dobrich Province | 0 | Bulgaria | BG-08 |
| Dobrna Municipality | 0 | Slovenia | SI-155 |
| Dobrova–Polhov Gradec Municipality | 0 | Slovenia | SI-021 |
| Dobrovnik Municipality | 0 | Slovenia | SI-156 |
| Dojran Municipality | 0 | Republic of North Macedonia | MK-26 |
| Dol pri Ljubljani Municipality | 0 | Slovenia | SI-022 |
| Dolenjske Toplice Municipality | 0 | Slovenia | SI-157 |
| Dolneni Municipality | 0 | Republic of North Macedonia | MK-27 |
| Domagnano | 0 | San Marino | SM-03 |
| Domažlice | 0 | Czech Republic | CZ-321 |
| Domžale Municipality | 0 | Slovenia | SI-023 |
| Donetsk Oblast | 0 | Ukraine | UA-14 |
| DOR | 0 | United Kingdom | GB-DOR |
| Dornava Municipality | 0 | Slovenia | SI-024 |
| DOW | 0 | United Kingdom | GB-DOW |
| DR | 0 | Moldova | MD-DR |
| DR | 0 | Netherlands | NL-DR |
| Drama Regional Unit | 0 | Greece | GR-52 |
| Dravograd Municipality | 0 | Slovenia | SI-025 |
| DRS | 0 | United Kingdom | GB-DRS |
| Drugovo Municipality | 0 | Republic of North Macedonia | MK-28 |
| Druskininkai municipality | 0 | Lithuania | LT-07 |
| DRY | 0 | United Kingdom | GB-DRY |
| DS | 0 | Poland | PL-DS |
