- Maquoketa
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- Marble Rock
- Marcus
- Mardan Mobile Home Court
- Marengo
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- Marion Mobile Home Park
- Mark
- Marne
- Marquette
- Marquisville
- Marsh
- Marshalltown
- Martelle
- Martensdale
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- Mason City
- Mason City Junction
- Masonville
- Massena
- Massey
- Massillon
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- Maud