- Mare Island
- Maredith Mill
- Marian Place
- Mariana Ranchos
- Maricopa
- Mariemont
- Marin City
- Marina
- Marina del Rey
- Marine Terrace
- Marinwood
- Mariposa
- Mark West Springs
- Marklee Village
- Markleeville
- Marks Place
- Marne
- Mars
- Marsh Creek Springs
- Marsh Mill
- Marshall
- Marshall Junction
- Martell
- Martinez
- Martinez
- Martinez
- Martinez Place
- Martins
- Martins Beach
- Martinus Corner