New York - Criteria: A (event)
| Old Stone House of Brooklyn, The |
| Old Stone Warehouse |
| Old St. Patrick's Cathedral Complex |
| Old St. Peter's Church |
| Old Town Cemetery and Palatine Church Site |
| Old Town Green Historic District |
| Old Town Hall Historic District |
| Old Town of Flushing Burial Ground |
| Old Trees |
| Old Troy Hospital |
| Olean Armory |
| Olean Public Library |
| Olean School #10 |
| Oliver Avenue Bridge |
| Olivet Chapel |
| Olmstead Street Historic District |
| Onderdonk House |
| Oneida Armory |
| Oneida Community Mansion House |
| Oneida Lake Congregational Church |
| Oneonta Armory |
| Oneonta Downtown Historic District |
| Oneonta Theatre |
| Onesquethaw Valley Historic District |
| Onondaga Highlands-Swaneola Heights Historic District |
| Onondaga Park |
| Ontario and Western Railroad Passenger Station |
| Onteora Park Historic District |
| Oran District No. 22 Schoolhouse |
| Orange Mill Historic District |
| Orchard Shoal Light Station, Old |
| Orient Point Light Station |
| Oriskany Battlefield |
| Orleans County Courthouse Historic District |
| Ormonde |
| Ormsby-Laughlin Textile Companies Mill |
| Osceola Town Hall |
| Osgood, J.C., Firehouse |
| Oswegatchie Pumping Station |
| Oswego and Syracuse Railroad Freight House |
| Oswego City Hall |
| Oswego City Library |
| Oswego Meeting House and Friends' Cemetery |
| Oswego Yacht Club |
| Otis, Job and Deborah, House |
| Otsdawa Baptist Church |
| Otsego County Courthouse |
| Ottendorfer Public Library and Stuyvesant Polyclinic Hospital |
| Our Mother of Sorrows Roman Catholic Church Complex |
| 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 |
| Oyster Bay Long Island Rail Road Turntable |
| Packard Motor Car Showroom and Storage Facility |
| Packer Farm and Barkersville Store |
| Paddock Arcade |
| Paddock Building |
| PAD Factory, The |
| Pagan-Fletcher House |
| Pakatakan Artists Colony Historic District |
| Palace Theatre |
| Palatine Bridge Freight House |
| Palatine Church |
| Palatine German Frame House |
| Palmer Brook Bridge |
| Palmer-Lewis Estate |
| Palmyra Village Historic District |
| Parachute Jump |
| Paramount Studios Complex |
| Paramount Theatre |
| Park and Tilford Building |
| Park Avenue and State Street Historic District |
| Park Avenue Historic District |
| Park Church |
| Parker, Alton B., Estate |
| Parker Farmhouse |
| Parks-Bentley House |
| Parkside Candy Shoppe and Factory |
| Parkside East Historic District |
| Parkway Theatre |
| Parkway Village |
| Parmeter, Nathaniel, House |
| Parrott Hall |
| Partridge Cottage |
| Partridge-Sheldon House |
| Pastures Historic District |
| Patriot's Park |
| Patroon Agent's House and Office |
| Patterson-Hooper Family Cemetery |
| Pawling Hall |
| Payjack Chevrolet Building |
| Peabody, Royal C., Estate |
| Pease, Daniel and Miriam, House |
| Peck, Thomas, Farmhouse |
| Peck, Waltrous, House |
| Peebles (Peobles) Island |
| Peekskill Downtown Historic District |
| Peekskill Freight Depot |
Data from United States Park Service and Wikidata
