New York - Area of significance: Architecture
| Osborn-Bouton-Mead House |
| Osborne Apartments |
| Osborne House |
| Osburn, Mrs., House |
| Osgood, J.C., Firehouse |
| Oswegatchie Pumping Station |
| Oswego and Syracuse Railroad Freight House |
| Oswego Armory |
| Oswego City Hall |
| Oswego City Library |
| Oswego County Courthouse |
| Oswego Meeting House and Friends' Cemetery |
| Oswego-Oneida Streets Historic District |
| Oswego Theater |
| Oswego West Pierhead Lighthouse |
| Oswego Yacht Club |
| Otis, Job and Deborah, House |
| Otsdawa Baptist Church |
| Otsego County Courthouse |
| Ottendorfer Public Library and Stuyvesant Polyclinic Hospital |
| Otter Lake Community Church |
| Oulagisket |
| Our Lady of Victory National Shrine and Basilica Historic District |
| Our Lady of Victory Roman Catholic Church |
| Our Mother of Good Counsel Roman Catholic Church Complex |
| Our Mother of Sorrows Roman Catholic Church Complex |
| Oval Wood Dish Factory |
| Overackers Corners Schoolhouse |
| Overlook |
| Owasco Reformed Church |
| Owego Central Historic District |
| O & W Railroad Station at Port Ben |
| Oxford Village Historic District |
| Oyster Bay Long Island Rail Road Station |
| Packard Motor Car Showroom and Storage Facility |
| Packer Farm and Barkersville Store |
| Paddock Arcade |
| Paddock Building |
| Paddock Mansion |
| Paddy’s Market Historic District |
| PAD Factory, The |
| Page House |
| Pakatakan Artists Colony Historic District |
| Palace Theatre |
| Palatine Bridge Freight House |
| Palatine Bridge Historic District |
| Palatine Church |
| Palatine German Frame House |
| Palen, Frank A., House |
| Palmer Brook Bridge |
| Palmer-Lewis Estate |
| Palmyra Village Historic District |
| Pangburn, Stephen, House |
| Pantigo Road Historic District |
| Paramount Theatre |
| Park Avenue and State Street Historic District |
| Park Avenue Historic District |
| Park Avenue Historic District |
| Park Avenue Houses |
| Park Church |
| Parke Apartments |
| Park East Synagogue, Congregation Zichron Ephraim |
| Parker 13-Sided Barn |
| Parker, Alton B., Estate |
| Parker, Charles, House |
| Parker Farmhouse |
| Parker Training Academy Dutch Barn |
| Park Mart |
| Park Place Historic District |
| Park Plaza Apartments |
| Park Row Building |
| Parks-Bentley House |
| Parks, George H., House |
| Parkside Candy Shoppe and Factory |
| Parkside East Historic District |
| Parkside West Historic District |
| Park Slope Historic District |
| Park Square Historic District |
| Parkway Theatre |
| Parkway Village |
| Parmeter, Nathaniel, House |
| Parrott Hall |
| Parry House |
| Parry, John E., House |
| Parsonage Road Historic District |
| Parsonage, The |
| Parsons, Ambrose, House |
| Partridge Cottage |
| Partridge-Sheldon House |
| Pastures Historic District |
| Patchett House |
| Patroon Agent's House and Office |
| Patten, Jacob H., House |
| Patterson Farmhouse |
| "Patton, James ""Squire,"" House" |
| Pawling Hall |
| Payjack Chevrolet Building |
| Payne Avenue High School |
| Payne Cobblestone House |
| Payne, Col. Oliver Hazard, Estate |
Data from United States Park Service and Wikidata
