M
- Machin, California – Tim N. Machin
- Macon, 3 places in Georgia/Missouri/North Carolina – Nathaniel Macon
- Madelia, Minnesota – Madelia Hartshorn (deceased daughter of founder Philander Hartshorn)
- Madison, Maine and Madison, Wisconsin – James Madison
- Madison, South Dakota – James Madison (indirectly, via Madison, Wisconsin)
- Madison County, Florida – James Madison, fourth President of the United States of America
- Manchester, Vermont – Robert Montagu, 3rd Duke of Manchester
- Mandala, California – Mandala Kneeland (early settler)
- Mansfield, Massachusetts – William Murray, 1st Earl of Mansfield
- Mansfield, Ohio – Jared Mansfield (U.S. Surveyor General)
- Mansfield, Texas – R.S. Man and Julian Feild (settlers) (note spelling)
- Mariaville, Maine – Maria Matilda (daughter of landholder William Bingham)
- Marinette, Wisconsin – Marie Antoinette Chevalier (common-law wife of an early fur trader)
- Marion – Francis Marion (Revolutionary War hero), 14 places in
- Alabama – Illinois – Indiana – Iowa – Kansas – Kentucky – Louisiana – Massachusetts – Mississippi – New York – North Carolina – Ohio – South Carolina – Virginia
- Marion, North Dakota – Marion Mellen (daughter of Charles Sanger Mellen)
- Marion, Oregon – Francis Marion (Revolutionary War hero) (indirectly, via Marion County, Oregon)
- Marion, South Dakota – Marion Merrill (daughter of S.S. Merrill, a railroad official)
- Marion, Texas – Marion Dove (granddaughter of Joshua W. Young, owner of a plantation that the Galveston, Harrisburg and San Antonio Railway passed through)
- Marion County, Florida – General Francis Marion of South Carolina, a guerilla fighter and hero of the American Revolutionary War.
- Marsh Creek Springs, California – John Marsh
- Marshall, Texas – John Marshall
- Marklee Village, California – Jacob Marklee (early settler)
- Markleeville, California – Jacob Marklee (early settler)
- Marlboro, Vermont – John Churchill, Duke of Marlborough
- Marlborough, Massachusetts and Marlborough, New York – John Churchill, Duke of Marlborough
- Marlborough, New Hampshire – John Churchill, Duke of Marlborough (indirectly, via Marlborough, Massachusetts)
- Martendale, California – Harry J. Marten (founder)
- Martin County, Florida – John W. Martin 24th Governor of Florida
- Martinez, California – Don Ygnacio Martínez
- Martins Ferry, California – John F. Martin (first postmaster and ferry operator)
- Martinus Corner, California – Jan Henry Martinus (landowner)
- Maryland – Queen Henrietta Maria of France
- Maryland, New York – Queen Henrietta Maria of France (indirectly, via the state of Maryland)
- Marysville, California – Mary Murphy Covillaud (Donner Party survivor)
- Maryville, Missouri – Mary Graham (wife of Amos Graham, county clerk)
- Masaryktown, Florida – Tomáš Garrigue Masaryk (Czechslovak President)
- Mason, New Hampshire – Captain John Mason (New Hampshire's founder)
- Masonville, New York – Rev. John M. Mason (landholder)
- Mathis, Texas – Thomas Henry Mathis (proprietor)
- Mattos, California – John Garcia Mattos, Sr. (early settler)
- Maupin, Oregon – Howard Maupin (settler who established a farm and ferry here)
- Mauriceville, Texas – Maurice Miller (son of the first president of the Orange and Northwestern Railway)
- Mauston, Wisconsin – Milton M. Maughs (founder)
- Maynard, Massachusetts – Amory Maynard (mill owner)
- McAllen, Texas – John McAllen (settler)
- McCann, California – William O. McCann (lumber mill operator)
- McFarland, California – J.B. McFarland (founder)
- McGraw, New York – Samuel McGraw
- McHenry, Illinois – William McHenry
- McKinleyville, California – President William McKinley
- McKittrick, California – Capt. William McKittrick (local landowner and rancher)
- McMinnville, Tennessee – Joseph McMinn
- Mead, Colorado – Dr. Martin Luther Mead (landowner)
- Mendenhall Springs, California – William M. Mendenhall (health spa proprietor)
- Mercer, Maine – Brigadier General Hugh Mercer (Revolutionary War hero)
- Mercey Hot Springs, California – J.N. Mercy (early settler)
- Meredith, New Hampshire – Sir William Meredith, 3rd Baronet (member of British Parliament)
- Merritt, California – Hiram P. Merritt (early settler)
- Methuen, Massachusetts – Sir Paul Methuen (British diplomat)
- Mettler, California – W.H. Mettler (local agriculturalist)
- Metz, California – W.H.H. Metz (first postmaster)
- Meyers, California – George Henry Dudley Meyers (early landowner)
- Micanopy, Florida – Micanopy, leading chief of Seminoles, led the tribe during the Second Seminole War.
- Middleton, New Hampshire – Sir Charles Middleton, 1st Baron Barham
- Milan, New Hampshire – Milan Harris (mill owner)
- Milbank, South Dakota – Jeremiah Milbank (railroad director)
- Miles City, Montana – General Nelson A. Miles
- Miley, California – Julian J. Miley (first postmaster)
- Millbrae, California – Darius Ogden Mills
- Miller, California – James Miller (early settler)
- Millerton, Marin County, California – James Miller (wharf owner)
- Millerton, New York – Sidney Miller (railroad contractor)
- Milliken, Colorado – John D. Milliken (railroad official)
- Millis, Massachusetts – Lansing Millis (railroad executive)
- Millsaps, California – George W. Millsaps (early settler)
- Millsholm, California – Edgar Mills (landowner)
- Millspaugh, California – Almon N. Millspaugh (first postmaster)
- Milo, Maine – Milo of Croton (famous athlete from Ancient Greece)
- Milton, California – Milton Latham (railroad engineer)
- Minear, California – John J. Minear (first postmaster)
- Minkler, California – Charles O. Minkler (local farmer)
- Minot, Maine – Judge Minot of the General Court (aided in the town's incorporation)
- Minturn, California – Jonas and Thomas Minturn (local farmers)
- Mitchell, South Dakota – Alexander Mitchell (president of the Chicago, Milwaukee, St. Paul and Pacific Railroad)
- Modesto, California – William Chapman Ralston, reputed for being a modest man
- Monroe – James Monroe, 11 places in
- Connecticut – Maine – Massachusetts – Michigan – New Hampshire – New Jersey – New York – North Carolina – Ohio – Utah – Washington
- Monroeville, California – U.P. Monroe (founder)
- Monroeville, Pennsylvania – Joel Monroe (first postmaster)
- Monson, Maine – Sir John Monson (indirectly, via Monson, Massachusetts)
- Monson, Massachusetts – Sir John Monson
- Montgomery, 4 places in Alabama/Massachusetts/Minnesota/New York – General Richard Montgomery
- Montgomery, Texas – Andrew J. Montgomery (trading post establisher)
- Mooney Flat, California – Thomas Mooney (trading post & hotel establisher)
- Moorcroft, Wyoming – Alexander Moorcroft (settler)
- Moores Flat, California – H.M. Moore (first settler))
- Moraga, California – Joaquin Moraga (explorer and landowner)
- Morgan, California – Charles Morgan (early settler)
- Morgan, Utah – Jedediah Morgan Grant (a leader in The Church of Jesus Christ of Latter-day Saints)
- Morgan, Vermont – John Morgan (landholder)
- Morgan's Point, Texas – Emily West Morgan (known as the Yellow Rose of Texas)
- Morgantown, West Virginia – Zackquill Morgan
- Morrill, Maine – Anson P. Morrill (governor of Maine)
- Morris, Connecticut – James Morris III (Revolutionary War soldier)
- Morris, New York – General Jacob Morris (son of Lewis Morris, a signer of the Declaration of Independence)
- Morris Plains, New Jersey – Lewis Morris (the first royal governor of New Jersey)
- Morris Township, New Jersey – Lewis Morris
- Morristown, New Jersey – Lewis Morris
- Morton Grove, Illinois – Levi P. Morton
- Moses Lake, Washington – Chief Moses (Native American chief of the Sinkiuse-Columbia)
- Moss, Monterey County, California – Charles Moss (wharf owner)
- Moss Landing, California – Charles Moss (wharf owner)
- Moultonborough, New Hampshire – Colonel Jonathan Moulton and others in his family
- Mount Bullion, Mariposa County, California – Senator Thomas Hart Benton (nicknamed "Old Bullion")
- Mount Pulaski, Illinois – Casimir Pulaski (Revolutionary War hero)
- Mount Washington, Kentucky and Mount Washington, Massachusetts – George Washington
- Mower, California – Lloyd W. Mower (first postmaster)
- Mullan, Idaho – John Mullan (builder of Mullan Road, a wagon route)
- Murdo, South Dakota – Murdo MacKenzie (Texas cattleman)
- Muroc, California – Ralph and Clifford Corum (early settlers) – Muroc is Corum spelled backwards
- Murphys, California – Daniel and John Murphy (early miners and settlers)
- Murray, California – David Murray (olive industry figure)
- Murray, Kentucky – John L. Murray (former Congressman from the area who had died two years before the city's incorporation in 1844)
- Murray, Utah – Eli Murray (territorial governor of Utah)
Read more about this topic: List Of American Places Named After People