M
- Mack
- Mad Creek
- Madrid
- Magnolia
- Maher
- Maitland
- Malachite
- Malta
- Manassa
- Mancos
- Manila
- Manitou Springs
- Manzanola
- Marble
- Marcott
- Mariano
- Marigold
- Marlman
- Marshall
- Marshdale
- Marvel
- Masonic Park
- Masonville
- Massadona
- Masters
- Matheson
- Matterhorn
- Maxeyville
- Maybell
- Mayday
- Maysville
- May Valley
- McClave
- McClellands
- McCoy
- McKenzie Junction
- Mead
- Medino Plaza
- Meeker
- Meeker Park
- Melina
- Meredith
- Meridian
- Merino
- Mesa
- Mesita
- Messex
- Meyers Corner
- Middleton
- Midland
- Midway
- Milliken
- Millwood
- Millwood
- Milner
- Mindeman
- Mineral Hot Springs
- Minturn
- Mishawaka
- Mitchell
- Model
- Moffat
- Mogote
- Molina
- Montbello
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- Monte Vista Estates
- Montezuma
- Montrose
- Monument
- Monument Park
- Moonridge
- Morey
- Morfield Village
- Morgan
- Morrison
- Mosca
- Moseley
- Mountain View
- Mountain Village
- Mount Crested Butte
- Mount Harris
- Mount Olivet
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- Mount Vernon Club Place
- Mt Massive Lakes
- Mt Princeton Hot Springs
- Muleshoe
- Mystic