1850 Atlas
| Name | What | Place | Pop | Other |
| Mountain | T | Hot Springs Co, AR | ||
| Mountain | T | Newton Co, MO | ||
| Mountain | T | Washington Co, AR | 909 | |
| Mountain Cove | PO | Fayete Co, VA | ||
| Mountain Creek | PO | Catawba Co, NC | ||
| Mountain Falls | PO | Frederick Co, VA | ||
| Mountain Grove | PO | Bath Co, VA | ||
| Mountain Home | PO | McDowell Co, NC | ||
| Mountain Home | PO | Lawrence Co, AL | ||
| Mountain Inn | PO | Tuolumne Co, CA | ||
| Mountain Shoals | PO | Spartanburgh dist, SC | ||
| Mountain Spring | PO | Martin Co, IN | ||
| Mountain Stand | PO | Marshall Co, AL | ||
| Mountain View | PO | Abbeville dist, SC | ||
| Mountville | PV | Loudoun Co, VA | ||
| Mountville | PV | Laurens dist, SC | ||
| Mountville | PV | Troup Co, GA | ||
| Mountville | PV | Lancaster Co PA | ||
| Mouth of Hewasee | PO | Meigs Co, TN | ||
| Mouth of Indian | PO | Monroe Co, VA | ||
| Mouth of Little River | PO | Blount Co, TN | ||
| Mouth of Poca | PO | Putnam Co, VA | ||
| Mouth of Sandy | PO | Henry Co, TN | ||
| Mouth of Seneca | PO | Pendleton Co, VA | ||
| Mouth of Wilson | PO | Grayson Co, VA | ||
| Mouth of Yellow Creek | PO | Jefferson Co, OH | ||
| Mowrystown | PO | Highland Co, OH | ||
| Moyamensing | T | Philadelphia Co, PA | 26,979 | suburban district of Philadelphia having an independent incorporation |
| Muchinippe | PO | Logan Co, OH | ||
| Muckalushy | PO | Neoshoba Co, MS | ||
| Mud Bridge | PO | Cabell Co, VA | ||
| Mud Creek | PO | St Clair Co, IL | ||
| Mud Creek | PO | McNairy Co, TN | ||
| Mud Creek | PO | Henderson Co, NC | ||
| Mud Creek | PO | Eaton Co, MI | ||
| Mud Lick | PO | Chatham Co, NC | ||
| Mud Spring | PO | El Dorado Co, CA | ||
| Muddy Creek | T | Butler Co, PA | 1,142 | |
| Muddy Creek | PO | Preston Co, VA | ||
| Muddy Creek | PO | Forsyth Co, NC | ||
| Muddy Creek Forks | PO | York Co, PA | ||
| Muddy Forks | PO | Cleveland Co, NC | ||
| Muddy Lane | PO | McDonough Co, IL | ||
| Muhlenburgh | PO | Luzerne Co, PA | ||
| Muhlenburgh | T | Pickaway Co, OH | 585 | |
| Muker | PO | Washington Co, WI | ||
| Mulberry | PO | Miami twp, Clermont Co, OH | ||
| Mulberry | PO | Wilkes Co, NC | ||
| Mulberry | PO | Jackson Co, GA | ||
| Mulberry | T | Franklin Co, AR | 532 | |
| Mulberry | T | Johnson Co, AR | 339 | |
| Mulberry | PO | Lincoln Co, TN | ||
| Mulberry Gap | PO | Hancock Co, TN | ||
| Mulberry Grove | PO | Harris Co, GA | ||
| Mulberry Grove | PO | Hopkins Co, KY | ||
| Mulberry Grove | PO | Bond Co, IL | ||
| Mull Grove | PO | Lincoln Co, NC | ||
| Mullico Hill | PV | Gloucester Co, NJ | water by Raccoon creek | |
| Mullica | T | Atlantic Co, NJ | 918 | |
| Mullingar | PO | Warren Co, PA | ||
| Mulloys | just has a P | Robertson Co, TN | ||
| Mumford | PO | Monroe Co, NY | ||
| Mumfordsville | PV, CH | Hart Co, KY | seat of justice, water by Green river | |
| Muncietown | PV, CH | Delaware Co, IN | seat of justice, water by White river | |
| Muncy | PB | Muncy Creek twp, Lycoming Co, PA | 901 | |
| Muncy | T | Lycoming Co, PA | 1,879 | water by Muncy & Loyalsock creeks |
| Muncy Creek | T | Lycoming Co, PA | 1,250 | water by Big & Little Muncy creeks |
| Mundy | T | Genesee Co, MI | 786 | |
| Munger's Mills | PO | Shannon Co, MO | ||
| Mungo Park | PO | Washington Co, PA | ||
| Munnsville | PO | Madison Co, NY | ||
| Munntown | PO | Washington Co, PA | ||
| Munnville | PV | Coshocton Co, OH | ||
| Munson | T | Geauga Co, OH | 1,193 | |
| Munsonville | PO | Cheshire Co, NH | ||
| Munster | PV | Alleghany twp, Cambria Co, PA | ||
| Murder Kill hundred | not listed | Kent Co, DE | ||
| Murdocksville | PV | Washington Co, PA | ||
| Murfreesborough | PV, CH | Rutherford Co, TN | seat of justice, water by tributary of Stone creek | |
| Murfreesborough | PV | Hertford Co, NC | water by Chowan river | |
| Murfreesborough | PO | Pike Co, AL | ||
| Murphy | PV, CH | Cherokee Co, NC | seat of justice, situated at the confluence of Hiawassee & Valley rivers | |
| Murphree's Valley | PO | Blount Co, AL | ||
| Murphys | PO | Calaveras Co, CA | ||
| Murphysboro | PO | Jackson Co, IL | ||
| Murphysville | PO | Mason Co, KY | ||
| Murray | PV | Wells Co, IN | ||
| Murray | PT | Orleans Co, NY | 2,520 | water by Sandy creek |
| Murray | PO | Callaway Co, KY | ||
| Murray's Ferry | PO | Williamsburgh dist, SC | ||
| Murraysville | PO | Jackson Co, VA | ||
| Murrill's Shop | PO | Nelson Co, VA | ||
| Murrinsville | PO | Butler Co, PA | ||
| Murrysville | PO | Franklin twp, Westmoreland Co, PA | ||
| Muscatine | PT | Muscatine Co, IA | 2,539 | seat of justice, water by Muscatine slue |
| Muscoda | PO | Grant Co, WI | ||
| Mushulaville | PO | Noxubee Co, MS | ||
| Muskeego | PT | Milwaukee Co, WI | ||
| Muskeego Centre | PO | Waukesha Co, WI | ||
| Muskegon | PO | Ottawa Co, MI | ||
| Musket | PO | Navarro Co, TX | ||
| Muskingum | PT | Muskingum Co, OH | 1,509 | |
| Mustang | PO | La Vaca Co, TX | ||
| Mutual | PO | Champaign Co, OH | ||
| Myatte | PO | Fulton Co, AR | ||
| Myersburgh | PO | Bradford Co, PA | ||
| Myersville | PO | Frederick Co, MD | ||
| Myer's Mills | PO | Vermilion Co, IL | ||
| Myrtle Springs | PO | Bowie Co, TX | ||
| Mystic | PV | Stonington twp, New London Co, CT | 89 | water by Mystic river |
| Mystic Bridge | PO | Groton twp, New London Co, CT | ||
| Mystic River | PO | New London Co, CT |