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- MacDougal, Daniel
- MacNeil, Donald and Bessie
- Maddock, Thomas
- Magee, John
- Magma Copper Company
- Maguire, Charles B.
- Mackey, Malcolm (Railroad collection)
- Mammoth, Arizona School Census
- Manley, Catherine
- Mansfeld Family
- Mansfeld, Leonor P.
- Manuscripts (Anonymous)
- Maricopa Bakery
- Maricopa County Legal Aid Society
- Maricopa County Real Property Maps
- Mariner’s Juvenile Band
- Marston, Otis
- Marteney, William M.
- Martin, Andrew P.
- Martin, Edith Peach Slaughter
- Martin, George
- Martin, Keith
- Martini, Jacob
- Mason, Gertrude F.
- Mathews, Rena
- Mathews, William R.
- Mathewson, Edward
- Mathieson, Art
- Matson, Andrew
- Matthews, John
- Maxey, Flynn
- Maxon, Mason
- Mayo, William
- Mazzanovich, Anton
- McCaffry, James E.
- McCarty, Kiernan
- McClintock-Halseth
- McClintock, James H.
- McCord, Warren
- McCormick, Ada
- McCormick, Richard
- McDaniel Family
- McDougall, Leslie
- McDowell, David
- McFate, Roy
- McKale, James F.
- McKee, J. H.
- McKinney, Benjamin
- McNair, John
- McNamee, Dorothy D.
- McNulty, James F. Jr.
- McPhaul, Harry H.
- McRae, Madge Barkley
- Medical Accounts Ledger
- Medigovich, Sam V.
- Melick, Dermont W.
- Menager, Joseph
- Menager, Louis
- Merrill, Nellie A
- Mesquite Garden Club
- Metzger, Jeremiah
- Mexican Imprints
- Mexican Labor History Research
- Mexico, Holy Office of Inquisitions
- Mexico & U. S. Border Microfilm Collection
- Meyer, Charles H.
- Microfilm Collection, Arizona Historical Foundation
- Microfilm Collection, Tucson
- Midgley Bridge Dedication Book
- Miles, Nelson
- Military Muster Rolls
- Military Post Inspection Reports
- Millar, Leslie
- Miller, Grover C.
- Miller, James H.
- Miller, Loye H.
- Miller, Silver Carl
- Miller, William N.
- Milner, Dana T.
- Milton Hospital Patient Register
- Milton, Jefferson and Mildred
- Milton, Mildred Taitt
- Minas Grandes Gold Mines Company
- Mines & Mining Ledger
- Ming Family
- Mining Oral Histories
- Miscellaneous Drawings, Maps & Charts
- Moctezuma Copper Company
- Monarch Lead Company
- Monro, Elbert and Dorothy
- Montana Mine
- Monte Cristo Copper Company
- Montgomery, Frances and Mary
- Montgomery, John B.
- Montgomery, Monte & Rozella
- Moore, Martha Herrick
- Moore, Yndia S.
- Morajeska, Victor & Alice
- Moreno, Benito
- Morgan, Henry A.
- Morning Star Group of Mining Claims
- Morris Family
- Morrison, Robert
- Morton, Charles
- Mott, Harvey L.
- Mountain View Hotel
- Mowry Mines
- Munk, J. A.
- Munro, George
- Murdoch, Will
- Murdock, John
- Murphey, John W.
- Murphey, Walter E.
- Murphey, Walter Sr.
- Murphy, James M.
- Murphy, Lawrence
- Murphy, Lewis
- Murray, Bredett C.
- Musicians Club Records
- Myerson, Hyman
