All - Constructed - 1900–1909
| Muncie Public Library |
| Municipal Ferry Pier |
| Municipal Light Plant |
| Munsell, William O., House |
| Murillo Flats |
| Murphey-Jennings House |
| Murphy, Daniel F., House |
| Murray Theater |
| Musketaquid Mills |
| Nampa Depot |
| National Guard Statistical Building |
| National Loan and Exchange Bank Building |
| National Metropolitan Bank Building |
| National Teacher's Normal and Business College Administration Building |
| Nativity BVM Cathedral |
| Navajo National Monument |
| NCO Railway Depot |
| Neet Bridge |
| Nesbitt, Amanda, House |
| Ness, Andres O., House |
| Nevada City Free Public Library |
| New Amsterdam Theater |
| New Brunswick Station |
| New Hayden Building |
| New Imperial Hotel |
| New London Ledge Lighthouse |
| New Main-Augsburg Seminary |
| New York Public Library |
| New York Public Library, 115th Street Branch |
| New York Public Library, Hamilton Grange Branch |
| New York School of Applied Design |
| New York Stock Exchange |
| Ney, Elisabet, Studio and Museum |
| Niagara Engine House |
| Nichols, J.L., House and Studio |
| Nickerson Mansion |
| Nicolai-Cake-Olson House |
| Nippon Kan |
| Nixon, Senator P. E., House |
| No. 5 Fire Station |
| Noble-Kendall House |
| Norbeck-Nicholson Carriage House |
| North, Austin, House |
| North Charlotte Historic District |
| Northcutts Cove Chapel |
| Northern Pacific Passenger Depot |
| Northern Pacific Railroad Settling Tanks |
| Northern Pacific Railway Depot and Freighthouse |
| Northern Pacific Warehouse |
| Northfield Town Hall |
| North Gypsum Creek Truss Leg Bedstead Bridge |
| Northwestern Terra Cotta Company Building |
| Norwegian Evangelic Lutheran Church and Cemetery |
| Noyes Hall, State School for the Deaf |
| Nuestra Senora de Lourdes Chapel |
| Nye County Courthouse |
| Oakes, Augustus J., House |
| Oakmont Country Club Historic District |
| Oaks Hotel |
| Odd Fellows Building |
| Odd Fellows Lodge |
| Ojala, Herman, Homestead |
| Oklahoma City University |
| Oklahoma College for Women Historic District |
| Oklahoma Publishing Company Building |
| Okolona College |
| Old A.C.L. Union Depot |
| Old Atoka State Bank |
| Old Cadillac City Hall |
| Old City Hall |
| Old Colony Club |
| Old First National Bank of Prineville, and Foster and Hyde Store |
| Old Hose House |
| Old Jacoby Creek School |
| Old Jefferson Parish Courthouse |
| Old Lawrence City Library |
| Old Library Building |
| Old Main, Augustana Academy |
| Old Napa Register Building |
| Old Ozaukee County Courthouse |
| Old South Mebane Historic District |
| Old St. Mary's Catholic Parish House |
| Old U.S. Post Office and Federal Building |
| Old Washington County Library |
| Old Woodley Park Historic District |
| Olmsted Station Powerhouse |
| Olson, Louis and Ellen, House |
| Onawa Public Library |
| Oneida Street Station |
| Orchestra Hall |
| Orem, Frank M., House |
| O'Shea Building |
| Oster, John, House |
| Otis Elevator Company Factory Building |
| Ottawa Library |
| Ottinger Hall |
| Our Lady of Perpetual Help Church |
| Oyler Mine |
| Pace House |
| Paddock, Colonel George H., House |
Data from United States Park Service and Wikidata
