- Maple (65 Companies)
- Maplewood (1 Company)
- Marathon (280 Companies)
- Marengo (55 Companies)
- Maribel (118 Companies)
- Marinette (2,826 Companies)
- Marion (210 Companies)
- Markesan (387 Companies)
- Marquette (14 Companies)
- Marshall (238 Companies)
- Marshfield (2,188 Companies)
- Mason (164 Companies)
- Mather (3 Companies)
- Mattoon (13 Companies)
- Mauston (1,112 Companies)
- Mayville (775 Companies)
- Mazomanie (244 Companies)
- Mcfarland (685 Companies)
- Mcnaughton (3 Companies)
- Medford (1,301 Companies)
- Mellen (124 Companies)
- Melrose (140 Companies)
- Menasha (1,463 Companies)
- Menomonee Falls (2,958 Companies)
- Menomonie (2,539 Companies)
- Mequon (2,643 Companies)
- Mercer (391 Companies)
- Merrill (1,256 Companies)
- Merrillan (105 Companies)
- Merrimac (76 Companies)
- Merton (24 Companies)
- Middle Inlet (1 Company)
- Middleton (2,911 Companies)
- Mikana (4 Companies)
