Idaho - Area of significance: Architecture
| Spencer, Edward S., House and Garage and the Fred Nelson Barn |
| Spencer, George, House |
| Spencer Rock House |
| Spirit Lake Historic District |
| Spokane & International Railroad Construction Camp |
| St. Agnes Catholic Church |
| St. Alphonsus' Hospital Nurses' Home and Heating Plant/Laundry |
| Standrod Bank |
| Standrod House |
| Stanley Ranger Station |
| State Bank of Kamiah |
| State Bank of Kooskia |
| State Street Historic District |
| St. Charles of the Valley Catholic Church and Rectory |
| Stephan, Louis, House |
| Sterry Hall |
| Steunenberg, A. K., House |
| Stevens, Arnold, House |
| Stewart, A. H., House |
| St. Gertrude's Convent and Chapel |
| Stickel, John, House |
| St. James Episcopal Church |
| St. James Episcopal Church |
| St. James' Episcopal Mission Church |
| St. John's Cathedral |
| St. John's Cathedral Block |
| St. Joseph's Catholic Church |
| St. Joseph's Catholic Church |
| St. Luke's Episcopal Church |
| St. Maries Masonic Temple No. 63 |
| St. Mary's Catholic Church |
| St. Mary's Catholic Church |
| St. Mary's Episcopal Church |
| Stoker, Henry, House and Outbuildings |
| Stone and Log Building |
| Stone Building |
| St Paul Missionary Baptist Church |
| St. Paul's Episcopal Church |
| St. Paul's Rectory and Sisters' House |
| Strahorn, Carrie Adell, Memorial Library |
| Stricker Store and Farm |
| St. Stanislaus Catholic Church |
| St. Stanislaus Kostka Mission |
| St. Thomas Catholic Church |
| Stucki, J. U., House and Outbuildings |
| Sugarloaf School |
| Sullivan-Kinney House |
| Sunnyside School |
| Sutton, John, House |
| Swanger Hall |
| Tamblyn, Agnes M., House |
| Taylor, Arthur, House |
| Taylor's Candy Factory |
| Teater, Archie, Studio |
| Telephone Company Bungalow |
| Terteling, Joseph A., House |
| Teton County Courthouse |
| Thomason Rice Barn |
| Thompson, Gaylord, House |
| Thompson Mortuary Chapel |
| Three-Room House |
| Thunborg, Jacob and Cristina, House |
| Tolleth House |
| Tooley, Don, House |
| Tourtellotte, John, Building |
| Trinity Episcopal Church |
| Trinity Episcopal Church |
| Trinity Methodist Church |
| Tueller, Jacob, Jr., House |
| Tueller, Jacob, Sr., House |
| Turner Hotel |
| Turner, John G., House |
| Tuttle, Bishop Daniel S., House |
| Twenty-One Ranchhouse |
| Twin Falls Bank and Trust Company Building |
| Twin Falls City Park Historic District |
| Twin Falls Downtown Historic District |
| Twin Falls Original Townsite Residential Historic District |
| Twin Falls Warehouse Historic District |
| Twin Peaks Sports |
| Underwood Hotel |
| Union Block and Montandon Buildings |
| Union Pacific Mainline Depot |
| United Presbyterian Church |
| University of Idaho Gymnasium and Armory |
| Upper Brownlee School |
| Upper Twin Lakes School |
| U.S. Inspection Statio-Porthill, Idaho |
| U.S. Post Office |
| US Post Office-Blackfoot Main |
| US Post Office-Bonners Ferry Main |
| US Post Office-Buhl Main |
| US Post Office-Caldwell Main |
| US Post Office-Kellogg Main |
| US Post Office-Nampa Main |
| US Post Office-Orofino Main |
| US Post Office-Payette Main |
| US Post Office-Preston Main |
| US Post Office-Wallace Main |
| Ustick School |
Data from United States Park Service and Wikidata
