Illinois - Significance region: Local
| Mattfeldt, Theodore H. O., House |
| Mattis, George and Elsie, House |
| Maverick Lloyd, Lola, House |
| Maxwell-Briscoe Automobile Company Showroom |
| Mayfair Apartments |
| Maynard, Isaac N., Rowhouses |
| Maywood Fire Department Building |
| McClintock, John and Amelia, House |
| McClure, Thomas J. and Caroline, House |
| McCormick, Charles Emmor, House |
| McFarland House |
| McGovney-Yunker Farmstead |
| McGrath, John, House |
| McJunkin, William, House |
| Meekerville Historic District |
| Memorial Bandstand of Long Point |
| Memorial Hall |
| Memorial Washington Reformed Presbyterian Church |
| Mercer County Courthouse |
| Mercer County Fairgrounds |
| Mercer County Jail |
| Mershon, Joab, House |
| Methodist Episcopal Church |
| Meyer, Pearl and Bess, House |
| Mid-City Trust and Savings Bank |
| Middle Avenue Historic District |
| Midwest Athletic Club |
| Milk, Lemuel, Carriage House |
| Miller, Allan, House |
| Miller, Bell, Apartments |
| Miller-Davis Law Buildings |
| Miller, George H., House |
| Miller, Henry W., House |
| Miller, Joseph, House |
| Millville Town Site |
| Millward, Caroline, House |
| Miners Institute Building |
| Moats, William, Farm |
| Mobile and Ohio Railroad Depot |
| Moline Downtown Commercial Historic District |
| Monmouth Courthouse Commercial Historic District |
| Montgomery County Courthouse |
| Montgomery, John Rogerson, House |
| Monticello Courthouse Square Historic District |
| Moore, C. H., House |
| Morgan County Courthouse |
| Morris Downtown Commercial Historic District |
| Morrison Main Street Historic District |
| Morris Wide Water Canal Boat Site |
| Morse, Robert Hosmer, House |
| Morton, Asher, Farmstead |
| Morton, J. Sterling, High School East Auditorium |
| Moss, Henry Clay, House |
| Motley, John Lothrop, School |
| Motor Row Historic District |
| Moultrie County Courthouse |
| Mount Carroll Historic District |
| Mount Lookout |
| Mount Morris Downtown Historic District |
| Mount Sterling Commercial Historic District |
| Muirhead, Robert and Elizabeth, House |
| Muller House |
| Municipal Courts Building |
| Murphysboro Downtown Historic District |
| Murphysboro Elks Lodge |
| Murphysboro Masonic Lodge No. 498 A.F & A.M |
| Music Pavilion |
| Narodni Sin |
| Narragansett, The |
| Near North Historic District |
| Neuville, The |
| Newcomb, Richard F., House |
| Nichols, Harry H., House |
| Nisbet Homestead Farm |
| Noble-Seymour-Crippen House |
| Normal Theater |
| Northeast Evanston Historic District |
| North Eighth Street Plaza |
| North Geneva Historic District |
| North Grove School |
| North Mayfair Bungalow Historic District |
| North Sangamon United Presbyterian Church |
| North Side Historic District |
| North State Street Historic District |
| North Wells Street Historic District |
| Norwood Park Historical District |
| Notre Dame de Chicago |
| Oak Circle Historic District |
| Oakland Cemetery Historic District |
| Oak Park Conservatory |
| Oak Park Village Hall |
| Oak Ridge Cemetery |
| Oakton Historic District |
| O'Connell, Daniel, House |
| O'Conor, Andrew J., III, House |
| Octagon House |
| Odd Fellows Opera Block |
| Odell Building |
| O'Grady, Mr. J. William de Coursey, House |
| Old Fire Station |
Data from United States Park Service and Wikidata
