1850 Atlas
| Name | What | Place | Pop | Other |
| Martha Furnace | PO | Centre Co, PA | ||
| Martha Furnace | PO | Hardin Co, IL | ||
| Martha Mills | PO | Fleming Co, KY | ||
| Marthasville | PO | Macon Co, GA | ||
| Marthasville | PV | Warren Co, MO | ||
| Martha's Vineyard | PO | Chatham Co, NC | ||
| Martickville | PV | Martick twp, Lancaster Co, PA | ||
| Martick | PT | Lancaster Co, PA | water by Beaver, Muddy & Recquea creeks, Susquehanna river | |
| Martin | T | Pope Co, AR | ||
| Martin | PT | Allegan Co, MI | 329 | |
| Martindale | PO | Mecklenburg Co, NC | ||
| Martinez | PO | Contra Costa Co, CA | ||
| Martinsburgh | PT, CH | Lewis Co, NY | 2,677 | seat of justice, water by Martin's creek & Black river |
| Martinsburgh | PV | Woodberry twp, Blair Co, PA | 442 | water by tributaries of Frankstown brnach of Juniata river |
| Martinsburgh | PV, CH | Berkley Co, VA | 1,930 | seat of justice |
| Martinsburgh | V | Monroe Co, KY | ||
| Martinsburgh | PV | Clay twp, Knox Co, OH | ||
| Martinsburgh | PV | Washington Co, IN | ||
| Martinsburgh | PO | Pike Co, IL | ||
| Martinsburgh | PO | Ripley Co, MO | ||
| Martin's Creek | PO | Northanpton Co, PA | ||
| Martin's Creek | PO | Carroll Co, TN | ||
| Martin's Creek | PO | Pickens dist, SC | ||
| Martin's Ferry | PO | Belmont Co, OH | ||
| Martin's Hill | PO | Catlin twp, Chemung Co, NY | ||
| Martin's Landing | PO | Perry Co, IN | ||
| Martin's Lime Kilns | PO | Stokes Co, NC | ||
| Martin's Store | PO | Macon Co, GA | ||
| Martinsville | PO | Somerset Co, NJ | ||
| Martinsville | PV, CH | Henry Co, VA | seat of justice, water by Smith's river | |
| Martinsville | PV | Clinton Co, OH | ||
| Martinsville | PV, CH | Morgan Co, IN | seat of justice | |
| Martinsville | PV | Clark Co, IL | 1,131 | water by north fork of Embarrass river |
| Martinsville | PO | Lancaster Co, PA | ||
| Martinsville | PO | Niagara Co, NY | ||
| Martville | PV | Sterling twp, Cayuga Co, NY | water by Sodus creek | |
| Marvel | PO | Bates Co, MO | ||
| Marvin | PO | Chautauque Co, NY | ||
| Mary | PO | Pulaski Co, AR | ||
| Mary Ann | T | Licking Co, OH | 999 | |
| Maryland | PT | Otsego Co, NY | 2,152 | water by Scheneva's creek |
| Maryland Line | PO | Baltimore Co, MD | ||
| Marysville | PV, CH | Union Co, OH | 605 | seat of justice, water by Mill creek |
| Marysville | PV | Campbell Co, VA | water by Stanton river | |
| Marysville | PV | Blount Co, TN | seat of justice, water by tributary of Pistol creek | |
| Marysville | PO | Paulding Co, GA | ||
| Marysville | PO | Benton Co, IA | ||
| Marysville | PO | Yuba Co, CA | ||
| Marysville | PO | Noddaway Co, MO | ||
| Masardis | PO | Aroostook Co, MO | ||
| Mascoutah | PV | St Clair Co, IL | ||
| Mashapang | PO | Tolland Co, CT | ||
| Maskegon | T | Ottowa Co, MI | 484 | water by Maskegon lake |
| Mason | PT | Hillsborough Co, NH | 1,626 | water by Souhegan river & tributaries of the Nashua river |
| Mason | PO | Warren Co, OH | ||
| Mason | T | Lawrence Co, OH | 1,132 | water by Symmes creek |
| Mason | T | Cass Co, MI | 1,259 | |
| Mason | T | Ingham Co, MI | 462 | |
| Mason | PT | Marion Co, MO | ||
| Mason Centre | PV | Ingham Co, MI | water by Sycamore creek | |
| Mason Hall | PO | Orange Co, NY | ||
| Mason Village | PV | Mason twp, Hillsborough Co, NY | ||
| Mason's Grove | PO | Madison Co, TN | ||
| Masontown | PO | Fayette Co, PA | ||
| Masonville | PT | Delaware Co, NY | 1,550 | water by tributaries of Susquehanna & Delaware rivers |
| Masonville | PV | Lauderdale Co, AL | ||
| Maspeth | PO | Queen's Co, Long Island, NY | ||
| Massack | PO | McCracken Co, KY | ||
| Massamutton | PO | Page Co, VA | ||
| Massena | PT | St Lawrence Co, NY | 2,870 | water by Racket, Grass and St Lawrence rivers |
| Massena Centre | PO | Massena twp, St Lawrence Co, NY | ||
| Massey's Cross Roads | PO | Kent Co, MD | ||
| Massillon | PV | Perry twp, Stark Co, OH | on the Ohio canal | |
| Massillon | PO | Allen Co, IN | ||
| Massillon | PO | Clinton Co, IA | ||
| Masten's Corner | PO | Kent Co, DE | ||
| Mastersonville | PO | Lancaster Co, PA | ||
| Masterton | PO | Monroe Co, OH | ||
| Mast Yard | PO | Merrimack Co, NH | ||
| Matagorda | PV | Matagorda Co, TX | (seat of justice) | |
| Matamora | PO | Hardeman Co, TN | ||
| Matamoras | PO | Montgomery Co, NC | ||
| Matherton | PO | Iowa Co, MI | ||
| Matildaville | PO | Clarion Co, PA | ||
| Matildaville | PO | Parishville twp, St Lawrence Co, NY | ||
| Mattapoiset | PV | Rochester twp, Plymouth Co, MA | water by an outlet of Buzzard's bay | |
| Mattaqamkeag | PO | Penobscot Co, ME | ||
| Mattawan | PV | Van Buren Co, MI | ||
| Mattawan | PV | Fishkill twp, Dutchess Co, NY | water by Fishkill creek | |
| Matthews | PV, CH | Matthews Co, VA | seat of justice | |
| Matthew's Mills | PO | Richland Co, IL | ||
| Matthew's Store | PO | Anne Arundel Co, MD | ||
| Mattison | PT | Branch Co, MI | 475 | |
| Mattituck | PV | Southold twp, Suffolk Co, Long Island, NY | ||
| Mauch Chunk | PT | Carbon Co, PA | 3,727 | water by Lehigh river, Beaver, Mauch Chunk, Nesquihoning & Kettle creeks, Room run |
| Mauckport | PV | Harrison Co, IN | ||
| Maulding Mills | PO | Wayne Co, IL | ||
| Maumee | T | Allen Co, IN | ||
| Maumee City | PV, CH | Lucas Co, OH | seat of justice, water by Maumee river | |
| Maumelle | PO | Pulaski Co, AR | ||
| Maurice River | T | Cumberland Co, NJ | 2,245 | water by Delaware bay & Tuckahoe, Tarkill & Maurice rivers |
| Mauricetown | PV | Downe twp, Cumberland Co, NJ | water by Maurice river | |
| Maurius | PO | Vigo Co, IN | ||
| Mavais | PO | Osage Co, MO | ||
| Maxatawny | T | Berks Co, PA | 1,740 | water by Maiden & Sacony creeks |
| Maxey | PO | Oglethorpe Co, GA | ||
| Maxfield | PT | Penobscot Co, ME | 186 | water by Piscataquis river & Sebasi stream |
| Maxwell | PO | Delaware Co, OH | ||
| May | PO | Lancaster Co, PA | ||
| May Flower | PO | Otsego Co, NY | ||
| May Hill | PO | Lee Co, IL | ||
| Mayberry | PO | Lewis Co, MO | ||
| Maybinton | PV | Newberry dist, SC | ||
| Mayfield | T | Somerset Co, ME | 1,682 | |
| Mayfield | PT | Fulton Co, NY | 2,429 | water by tributaries of Sacondaga river |
| Mayfield | PO | Isle of Wight Co, VA | ||
| Mayfield | PV, CH | Graves Co, KY | seat of justice, water by tributary of Mayfield river | |
| Mayfield | PT | Cuyahoga Co, OH | 1,117 | water by Chagrin river |
| Mayfield | PO | Warren Co, GA | water by Ogeechee river | |
| Mayo | PO | Halifax Co, VA | ||
| Mayoning | PV | Patrick Co, VA | water by tributary of North Mayo river | |
| Mayport Mills | PO | Duval Co, FL | ||
| May's Landing | PV, CH | Hamilton twp, Atlantic Co, NJ | seat of justice, water by Great Egg Harbor river, at the head of sloop navigation | |
| May's Lick | PO | Mason Co, KY | ||
| Maysville | PV, CH | Buckingham Co, VA | seat of justice, water by Slate river | |
| Maysville | PV | Greenbrier Co, VA | ||
| Maysville | T | Morgan Co, OH | 1,512 | |
| Maysville | city | Mason Co, KY | 3,840 | water by Ohio river |
| Maysville | V | Fountain Co, IN | ||
| Maysville | PO | Huntington Co, IN | ||
| Maysville | PV, CH | Clay Co, IL | seat of justice | |
| Maysville | PO | Madison Co, AL | ||
| Maysville | PV, CH | De Kalb Co, MO | seat of justice | |
| Maysville | PO | Benton Co, AR | ||
| Maysville | PO | Yuba Co, CA | ||
| Maytown | PV | Donegal twp, Lancaster Co, PA | 634 | |
| Mayville | PV, CH | Chautauque Co, NY | seat of justice | |
| Mayville | PO | Dodge Co, WI | ||
| Mazon | PO | Grundy Co, IL |