| MRHS | Mainland Regional High School 
| Others |
| MRHS | Manchester Regional High School
| Others |
| MRHS | Maria Regina High School
| Others |
| MRHS | Marine Radio Historical Society
| Others |
| MRHS | Maritime Radio Historical Society
| Others |
| MRHS | Marriotts Ridge High School
| Others |
| MRHS | Marvin Ridge High School
| Others |
| MRHS | Mascenic Regional High School
| Others |
| MRHS | Matawan Regional High School
| Others |
| MRHS | Mature Respectful Honest And Safe
| Others |
| MRHS | Mesa Ridge High School
| Others |
| MRHS | Midwest Regional Health Services
| Others |
| MRHS | Midwest Regional Hosta Society
| Others |
| MRHS | Mill Reject Handling System
| Others |
| MRHS | Minnechaug Regional High School
| Others |
| MRHS | Monadnock Regional High School
| Others |
| MRHS | Monmouth Regional High School
| Others |
| MRHS | Monmouth-Roseville High School
| Others |
| MRHS | Monomoy Regional High School
| Others |
| MRHS | Morningside Retirement and Health Services
| Others |
| MRHS | Morningside Retirement Health Services
| Others |
| MRHS | Morton Ranch High School
| Others |
| MRHS | Mount Rainier High School
| Others |
| MRHS | Mountain Range High School
| Others |
| MRHS | Mountain Ridge High School
| Others |
| MRHS | Muskegon Railroad Historical Society
| Others |
| MRHS | Nacienda la Suerte, Costa Rica
| Others |