| | Marion County | OH | 39101 | | Marion, OH 32020 | Columbus-Marion-Zanesville,
OH 198 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=MarionCounty+OH |
| | Medina County | OH | 39103 | | Cleveland, OH 17410 | Cleveland-Akron-Canton,
OH 184 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=MedinaCounty+OH |
| | Meigs County | OH | 39105 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=MeigsCounty+OH |
| | Mercer County | OH | 39107 | | Celina, OH 16380 | Lima-Van Wert-Celina, OH 338 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=MercerCounty+OH |
| | Miami County | OH | 39109 | | Dayton-Kettering-Beavercreek,
OH 19430 | Dayton-Springfield-Kettering,
OH 212 | Outlying | metro county (urban) | manufacturing-dependent | https://maps.google.com/?q=MiamiCounty+OH |
| | Monroe County | OH | 39111 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=MonroeCounty+OH |
| | Montgomery County | OH | 39113 | | Dayton-Kettering-Beavercreek,
OH 19430 | Dayton-Springfield-Kettering,
OH 212 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=MontgomeryCounty+OH |
| | Morgan County | OH | 39115 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=MorganCounty+OH |
| | Morrow County | OH | 39117 | | Columbus, OH 18140 | Columbus-Marion-Zanesville,
OH 198 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=MorrowCounty+OH |
| | Muskingum County | OH | 39119 | | Zanesville, OH 49780 | Columbus-Marion-Zanesville,
OH 198 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=MuskingumCounty+OH |