Washington - Role: Building
| North Mowich Trail Shelter |
| Northport School |
| Northrop Primary School |
| Northwestern Improvement Company Store |
| Nuclear Reactor Building |
| Oakesdale City Hall |
| Oakland Block |
| Oatman, Earl, House |
| Ohanapecosh Comfort Station No. O-302 |
| Ohanapecosh Comfort Station No. O-303 |
| Okanogan County Courthouse |
| Old Capitol Building |
| Old City Hall |
| Old Georgetown City Hall |
| Old German Consulate |
| Old Indian Agency |
| Old Main |
| Old Main, Western Washington State College |
| Old Public Safety Building |
| Olsen, Ben, House |
| Olson, Louis and Ellen, House |
| Olson, Mary, Farm |
| Olympia National Bank |
| Olympia Public Library |
| Olympic Club |
| Olympic Club Saloon |
| Olympic Hotel |
| 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) |
| Orr, Nathaniel, House and Orchard |
| Orton, Charles W., House |
| Osterman House |
| Otis Hotel |
| 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 |
| Panama Hotel |
| Pantages Theatre |
| Paradise Inn |
| Paramount Theatre |
| Paris, Joseph, House |
| Park Department, Division of Playgrounds |
| Parkland Lutheran Children's Home |
| Parsons, William, House |
| Pasco Carnegie Library |
| Patnude, Charles, House |
| Pearson, D. O., House |
| Pearson House |
| Pelton Creek Shelter |
| Pend Oreille County Courthouse |
| Pend Oreille Mines and Metals Building |
| Perkins Building |
| Perkins, James A., House |
| Perrin, Winfield, House |
| Perry Creek Shelter |
| Petersen, H. S., House |
| Pettygrove, Benjamin S., House |
| Peyton Building and Peyton Annex |
| Phillips, Dr. John and Viola, House and Office |
| Phillips House |
| Pickering Farm |
| Pickett House |
| Pietrzycki, Dr. Marcel, House |
| Piollet, Victor & Jean, House |
| Pioneer Church |
| Pioneer Hall |
| Pittock House |
| Point Defiance Lodge |
| Point Defiance Streetcar Station |
| Point No Point Light Station |
| Polson, F. Arnold, House and Polson, Alex, Grounds |
| Pomeroy Farm |
| Port Stanley School |
| Port Townsend Carnegie Library |
| Post Office and Federal Office Building |
| Potter, H. W., House |
| Pounder Building |
| Powell House |
| President Hotel |
| Preston Community Clubhouse |
| Preston Hall |
| Pullman High School |
| Purple Point-Stehekin Ranger Station House |
| Puyallup Fish Hatchery |
| Pythian Temple |
| Queen Anne Club |
| Queen Anne High School |
| Queen Anne Post Office and Regional Headquarters |
| Queen Anne Public School |
| Radio Station KGY |
| Rainier Club |
Data from United States Park Service and Wikidata
