Washington - Area of significance: Architecture
| Olympic Hotel |
| Olympic National Park Headquarters Historic District |
| Olympus Guard Station |
| Opera House and I. O. O. F. Lodge |
| Opportunity Township Hall |
| Orcas Hotel |
| Orchard Terrace Apartments |
| Oregon Railway and Navigation Company Depot-Dayton (formerly Dayton Depot) |
| Osterman House |
| Otis Hotel |
| Oysterville Historic District |
| Pacific Brewing and Malting Company |
| Pacific Coast Company House No. 75 |
| Pacific County Courthouse |
| Pacific National Bank Building |
| Pacific Telephone and Telegraph Building |
| Pagani, Luigi and Aurora, House |
| Palmer, A.L., Building |
| Palmer, Eben and Cynthia, Farmstead |
| Palmer, O. K., House |
| Palouse Main Street Historic District |
| Pantages Theatre |
| Paradise Historic District |
| Paradise Inn |
| Paramount Theatre |
| Paris, Joseph, House |
| Park Butte Lookout |
| Park Department, Division of Playgrounds |
| Pasco Carnegie Library |
| Patnude, Charles, House |
| Patos Island Light Station |
| Peace Arch |
| Peaceful Valley Historic District |
| Pearson, D. O., House |
| Pearson House |
| Pelton Creek Shelter |
| Pend Oreille County Courthouse |
| Pend Oreille Mines and Metals Building |
| Pennsylvania Avenue-West Side Historic District |
| Perkins Building |
| Perkins, James A., House |
| Perrin, Winfield, House |
| Perry Creek Shelter |
| Petersen, H. S., House |
| Pettygrove, Benjamin S., House |
| Phillips, Dr. John and Viola, House and Office |
| Phillips House |
| Pickering Farm |
| Pietrzycki, Dr. Marcel, House |
| Pike Place Public Market Historic District |
| Piollet, Victor & Jean, House |
| Pioneer Building, Pergola, and Totem Pole |
| Pioneer Church |
| Pioneer Hall |
| Pittock House |
| Point Defiance Lodge |
| Point Defiance Streetcar Station |
| Point Robinson Light Station |
| Polson, F. Arnold, House and Polson, Alex, Grounds |
| Port Angeles Civic Historic District |
| Port Townsend Carnegie Library |
| Port Townsend Historic District |
| Post Office and Federal Office Building |
| Potter, H. W., House |
| Pounder Building |
| Powell House |
| Preston Community Clubhouse |
| Preston Hall |
| Pullman High School |
| Purple Point-Stehekin Ranger Station House |
| Puyallup Fish Hatchery |
| Pyramid Peak Aircraft Warning Service Lookout |
| Pythian Temple |
| Queen Anne High School |
| Queen Anne Public School |
| Quilcene Ranger Station |
| Radio Station KGY |
| Rainier Club |
| Rainier School |
| Ralston, Judge, House |
| Ramsay House |
| Randle Ranger Station-Work Center |
| Ravenna-Cowen North Historic District |
| Raymond-Ogden Mansion |
| Raymond Public Library |
| Raymond Theater |
| Redelsheimer-Ostrander House |
| Redmond City Park |
| Red Shield Inn |
| Region Six Personnel Training Station |
| Reiman, Samuel and Katherine, House |
| Reinhart-Young House |
| RELIEF (lightship) |
| Review Building |
| Rhodes, Henry A. and Birdella, House |
| Rhodesleigh |
| Rhodes Medical Arts Building |
| Riblet, Royal, House |
| Richardson-Jackson House |
| Richards, T.G., and Company Store |
Data from United States Park Service and Wikidata
