Washington - Area of significance: Engineering
| 12th Avenue South Bridge |
| 14th Avenue South Bridge |
| Agate Pass Bridge |
| Arboretum Sewer Trestle |
| Aurora Avenue Bridge |
| Baker River Bridge |
| Balfour Dock Building |
| Ballard Bridge |
| Baring Bridge |
| Barstow Bridge |
| Beverly Railroad Bridge |
| Blewett Arrastra |
| Boeing, William E., House |
| Boundary Hydroelectric Project |
| Building No. 105, Boeing Airplane Company |
| Burbank Homestead Waterwheel |
| Camp Six |
| Cape Disappointment Historic District |
| Capital Boulevard Crossing |
| Chicago, Milwaukee, St. Paul and Pacific Railroad: South Cle Elum Yard |
| Chittenden Locks and Lake Washington Ship Canal |
| City Waterway Bridge |
| Coke Ovens |
| Columbia River Bridge |
| Columbia River Bridge at Kettle Falls |
| Columbia River Bridge at Northport |
| Columbia River Bridge at Wenatchee |
| Covington Electrical Substation, Bonneville Power Administration |
| Cowen Park Bridge |
| Curlew Bridge |
| Cushman Hydroelectric Project Historic District |
| Cushman No. 1 Hydroelectric Power Plant |
| Cushman No. 2 Hydroelectric Power Plant |
| Deception Pass |
| Denver and Rio Grande Western Railroad Business Car No. 101 |
| Diablo Hydroelectric Power Plant |
| Donald-Wapato Bridge |
| Duckabush River Bridge |
| Dungeness River Bridge |
| Dybdall Gristmill |
| East 34th Street Bridge |
| Elwha River Bridge |
| Elwha River Hydroelectric Power Plant |
| Enloe Dam and Powerplant |
| Fairfax Bridge |
| FIREBOAT NO.1 |
| Fire Station No. 25 |
| Fort Worden |
| Fremont Bridge |
| F Street Bridge |
| Glines Canyon Hydroelectric Power Plant |
| Golden West Lodge Historic District |
| Goldsborough Creek Bridge |
| Gorge Hydroelectric Power Plants |
| Grand Coulee Bridge |
| Grande Ronde River Bridge |
| Grandview Road-Yellowstone Trail |
| Hanford B Reactor |
| Hanford, Edwin H., House |
| High Steel Bridge |
| Holley-Mason Building |
| Hoquiam River Bridge |
| Horseshoe Bend Placer Claim |
| Idaho and Wash. Northern RR Bridge |
| Indian Timothy Memorial Bridge |
| Jim Creek Bridge |
| Johnson Bridge |
| Lake Chelan Hydroelectric Power Plant |
| Lake Keechelus Snowshed Bridge |
| Little Falls Hydroelectric Power Plant |
| Long Lake Hydroelectric Power Plant |
| Longview Bridge |
| Lower Baker River Hydroelectric Power Plant |
| Manning-Rye Covered Bridge |
| Marshall Bridge |
| Marsh, Louis S., House |
| McMillin Bridge |
| Middle Fork Nooksack River Bridge |
| Monroe Street Bridge |
| Montlake Bridge |
| Moore Theatre and Hotel |
| Mount Baker Ridge Tunnel |
| MV KALAKALA (ferry) |
| Nisqually Power Substation |
| Nooksack Falls Hydroelectric Power Plant |
| Norman Bridge |
| North 21st Street Bridge |
| North 23rd Street Bridge |
| North Bonneville Archeological District |
| North Hamma Hamma River Bridge |
| Okanogan Project: Conconully Resevoir Dam |
| Orient Bridge |
| Patton Bridge |
| Penstock Bridge |
| Pioneer Square-Skid Road District |
| PIRATE (R-Class Sloop) |
| Purdy Bridge |
| Ralston, John and Mary, House |
| Ravenna Park Bridge |
| Red Mountain Railroad Bridge |
Data from United States Park Service and Wikidata
