| Mellieħa | 0 | Malta | MT-30 |
| Mělník | 0 | Czech Republic | CZ-206 |
| Mengeš Municipality | 0 | Slovenia | SI-072 |
| Mērsrags Municipality | 0 | Latvia | LV-063 |
| Metlika Municipality | 0 | Slovenia | SI-073 |
| Metropolitan City of Bari | 0 | Italy | IT-BA |
| Metropolitan City of Bologna | 0 | Italy | IT-BO |
| Metropolitan City of Cagliari | 0 | Italy | IT-CA |
| Metropolitan City of Catania | 0 | Italy | IT-CT |
| Metropolitan City of Florence | 0 | Italy | IT-FI |
| Metropolitan City of Genoa | 0 | Italy | IT-GE |
| Metropolitan City of Messina | 0 | Italy | IT-ME |
| Metropolitan City of Milan | 0 | Italy | IT-MI |
| Metropolitan City of Naples | 0 | Italy | IT-NA |
| Metropolitan City of Palermo | 0 | Italy | IT-PA |
| Metropolitan City of Reggio Calabria | 0 | Italy | IT-RC |
| Metropolitan City of Rome | 0 | Italy | IT-RM |
| Metropolitan City of Turin | 0 | Italy | IT-TO |
| Metropolitan City of Venice | 0 | Italy | IT-VE |
| Mežica Municipality | 0 | Slovenia | SI-074 |
| MFT | 0 | United Kingdom | GB-MFT |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| MG | 0 | Monaco | MC-MG |
| Mġarr | 0 | Malta | MT-31 |
| MH | 0 | Romania | RO-MH |
| MH | 0 | Ireland | IE-MH |
| MI | 6 | United States | US-MI |
| MI | 0 | Hungary | HU-MI |
| MI | 0 | Belarus | BY-MI |
| MIK | 0 | United Kingdom | GB-MIK |
| Miklavž na Dravskem Polju Municipality | 0 | Slovenia | SI-169 |
| Mirditë District | 0 | Albania | AL-MR |
| Miren–Kostanjevica Municipality | 0 | Slovenia | SI-075 |
| Mirna Municipality | 0 | Slovenia | SI-212 |
| Mirna Peč Municipality | 0 | Slovenia | SI-170 |
| Mislinja Municipality | 0 | Slovenia | SI-076 |
| ML | 0 | Spain | ES-ML |
| Mladá Boleslav | 0 | Czech Republic | CZ-207 |
| MLN | 0 | United Kingdom | GB-MLN |
| MM | 0 | Romania | RO-MM |
| MN | 6.875 | United States | US-MN |
| MN | 0 | Ireland | IE-MN |
| MO | 4.225 | United States | US-MO |
| MO | 0 | Russia | RU-MO |
| MO | 0 | Ireland | IE-MO |
| Mogila Municipality | 0 | Republic of North Macedonia | MK-53 |
| Mojkovac Municipality | 0 | Montenegro | ME-11 |
| Mokronog–Trebelno Municipality | 0 | Slovenia | SI-199 |
| Molėtai District Municipality | 0 | Lithuania | LT-27 |
| Molise | 0 | Italy | IT-67 |
| MON | 0 | United Kingdom | GB-MON |
| Montana Province | 0 | Bulgaria | BG-12 |
| Montegiardino | 0 | San Marino | SM-08 |
| Moravče Municipality | 0 | Slovenia | SI-077 |
| Moravica District | 0 | Serbia | RS-17 |
| Moravske Toplice Municipality | 0 | Slovenia | SI-078 |
| Moravskoslezský kraj | 0 | Czech Republic | CZ-80 |
| Møre og Romsdal | 0 | Norway | NO-15 |
| MOS | 0 | Russia | RU-MOS |
| Most | 0 | Czech Republic | CZ-425 |
| Mosta | 0 | Malta | MT-32 |
| MOW | 0 | Russia | RU-MOW |
| Mozirje Municipality | 0 | Slovenia | SI-079 |
| Mqabba | 0 | Malta | MT-33 |
| MRT | 0 | United Kingdom | GB-MRT |
| MRY | 0 | United Kingdom | GB-MRY |
| MS | 0 | Romania | RO-MS |
| MS | 7 | United States | US-MS |
| Msida | 0 | Malta | MT-34 |
| MT | 0 | United States | US-MT |
| Mtarfa | 0 | Malta | MT-35 |
| MTY | 0 | United Kingdom | GB-MTY |
| MUL | 0 | United Kingdom | GB-MUL |
| Municipality of Apače | 0 | Slovenia | SI-195 |
| Municipality of Cirkulane | 0 | Slovenia | SI-196 |
| Municipality of Ilirska Bistrica | 0 | Slovenia | SI-038 |
| Municipality of Krško | 0 | Slovenia | SI-054 |
| Municipality of Škofljica | 0 | Slovenia | SI-123 |
| Munxar | 0 | Malta | MT-36 |
| MUR | 0 | Russia | RU-MUR |
| Murska Sobota City Municipality | 0 | Slovenia | SI-080 |
| Muta Municipality | 0 | Slovenia | SI-081 |
| MV | 0 | Germany | DE-MV |
| Mykolaiv Oblast | 0 | Ukraine | UA-48 |
| MYL | 0 | United Kingdom | GB-MYL |
| MZ | 0 | Poland | PL-MZ |
| Náchod | 0 | Czech Republic | CZ-523 |
| Nadur | 0 | Malta | MT-37 |
| Naklo Municipality | 0 | Slovenia | SI-082 |
| Naukšēni Municipality | 0 | Latvia | LV-064 |
| Naxxar | 0 | Malta | MT-38 |
| NAY | 0 | United Kingdom | GB-NAY |
