All - Constructed - 1890–1899
| Murdock, Jack M., House |
| Nabers, Morrow and Sinnige, Building |
| Nash, Rev. J. Edward, Sr., House |
| National Union Building |
| Natoma Presbyterian Church |
| Natrona County High School |
| Naulakha |
| Nazareth Convent and Academy |
| Neal, W. Scott, House |
| Nebot, Zaldo de, Residencia |
| Nebraska Telephone Company Building |
| Neihardt, John G., Study |
| Neilson, N. S., House |
| Netcott-Pfeiffer House |
| New Holland Machine Company |
| New Kasson Apartments |
| Newland House |
| New Market Hotel and Store |
| New Mexico Military Institute Historic District |
| Newport News Middle Ground Light Station |
| Newsome, J. Thomas, House |
| Newton Street Railway Carbarn |
| New York Botanical Gardens |
| New York Public Library |
| New York State Capitol |
| New York Yacht Club |
| Nichols, John F., House |
| Nicolet Public School |
| Nielson, Hans Peter, Gristmill |
| Niles, Louville, House |
| Niles, Louville V., House |
| Niles Railroad Depot |
| Ninth District Lighthouse Depot |
| Niotaze Methodist Episcopal Church |
| Noble, Samuel, Monument |
| North Carolina School for the Deaf: Main Building |
| Northern Casket Company Building |
| Northern National Bank |
| Northern Pacific Office Building |
| Northrup House |
| Norwalk River Railroad Bridge |
| Nuckolls County Courthouse |
| Oakes Estate |
| Oakley, Ami and Amanda, House |
| O'Bannon Homestead |
| Oconomowoc Depot |
| Oconto County Courthouse |
| Oddfellows Hall |
| Odenweller, F. F.-James P. and Nettie Morey House |
| O'Flaherty, John, House |
| Ogunquit Memorial Library |
| O'Hara Waltham Dial Company |
| Ohio Institution for the Education of the Deaf and Dumb |
| Old Akron Post Office |
| Old Arkansas City High School |
| Old Ashland Post Office |
| Old Capitol Building |
| Old Central, Oklahoma State University |
| Old Chicago Historical Society Building |
| Old DeKalb County Courthouse |
| Old Fresno Water Tower |
| Old Grandin Library |
| Old Hamilton County Jail |
| Old Harbor U.S. Life Saving Station |
| Old Library Building |
| Old Main |
| Old Main, Almira College |
| Old Main at the Lutheran Home at Topton |
| Old Main Building |
| Old Main, Western Washington State College |
| Old Medford High School |
| Old Miller Hospital |
| Old Mill Road truss bridge over the Wickecheoke Creek |
| Old River Bridge |
| Old Rotation |
| Old Runnymede Church |
| Old Southeast Town Hall |
| Old Stone Church |
| Old Union County Courthouse |
| Old Wakulla County Courthouse |
| Old Water and Electric Light Plant |
| Olive Hotel |
| Oliver-Morton Farm |
| Oliver School |
| Olson, Erick Lehi and Ingrid Larsen, House |
| Olympia Mill |
| Omaha Hotel |
| Omaha Public Library |
| Omro Village Hall and Engine House |
| Oneida Cotton Mills and Scott-Mebane Manufacturing Company Complex |
| O'Neill, Buckey, Cabin |
| Opdyke, Sylvester, House |
| Orchard Shoal Light Station, Old |
| Oregon Masonic Lodge |
| Oregon Shortline Railroad Company Building |
| Oregon Water Tower and Pump House |
| Orfordville Depot |
| Orient Point Light Station |
| Osborne, Edmund B., House |
| Ott, Albert, House |
Data from United States Park Service and Wikidata
