All - Architectural style - Federal architecture
| Olney, Capt. Stephen, House |
| Onderdonk House |
| O'Neall, Abijah II, House |
| Oneida Lake Congregational Church |
| Opel, John, House |
| Opposition House |
| Orange Springs |
| Osgood Family House |
| Otis, (First) Harrison Gray, House |
| Otis, Job and Deborah, House |
| Otis, (Second) Harrison Gray, House |
| Our House |
| Owasco Reformed Church |
| Owen-Harrison House |
| Owens, Isaac, House |
| Owsley, Gov. William, House |
| Oyer, Christian, Jr., House |
| Packer Farm and Barkersville Store |
| Page, Christopher, House |
| Page, William House |
| Palmer, Isaac, House |
| Palmer, Thomas H., House |
| Palo Alto Plantation |
| Parker, Aaron Jr. and Susan, Farm |
| Parker House |
| Parker House |
| Parker, Joseph, House |
| Parker, William, House |
| Parmeter, Nathaniel, House |
| Parsonage, The |
| Parson's Bend |
| Parsons, Josiah K., Homestead |
| Parsons, Stephen, House |
| Partridge, Jabez, Homestead |
| Pascault Row |
| Passmore, George, House |
| Passmore, Mansel, House |
| Patchett House |
| Patterson, Burd, House |
| "Patton, James ""Squire,"" House" |
| Paul Family Farm |
| Paxton |
| Paxton Place |
| Peabody, George, House |
| Peachcroft |
| Pearson, Abiel, House |
| Pease, Daniel and Miriam, House |
| Pease Homestead |
| Pecan Grove |
| Peck-Bowen House |
| Pembroke Friends Meetinghouse |
| Pender, Joseph John, House |
| Pennock, Martha, House |
| Pennsylvania Furnace Mansion |
| Pennsylvania House |
| Pennypacker, Benjamin, House |
| Pepper, Carlton, David, Farm |
| Perkins House |
| Perkins, Nicholas Tate, House |
| Perkins-Rockwell House |
| Perley, Sam, Farm |
| Perry, David, House |
| Perryville Tavern |
| Person Place |
| Peterborough Unitarian Church |
| Peters, John, House |
| Peterson, Canute, House |
| Peyton House |
| Pfeiffer, John Gottlieb, House |
| Phaup, William, House |
| Phelps-Jones House |
| Phelps, Stephen, House |
| Phillips' Folly |
| Phlegar Farm |
| Phoenix Building |
| Piedmont |
| Pinehurst Hall |
| Pineview |
| Pinkham, Daniel, House |
| Pinto, William, House |
| Piper House |
| Pisgah Presbyterian Church |
| Pitts-Inge |
| Pittston Congregational Church |
| Plain Dealing |
| Plain Farm House |
| Platt-Cady Mansion |
| Platt, Charles C., Homestead |
| Pleasant Prospect |
| Pleasant Retreat Academy |
| Pledger, Jacob, House |
| Plumb House |
| Plummer Homestead |
| Plymouth Antiquarian House |
| Poague House |
| Point of Honor |
| Polk, James K., House |
| Polk Sisters' House |
| Pool Rock Plantation |
| Poplar Hill Mansion |
Data from United States Park Service and Wikidata
