Idaho - Significance region: Local
| Smedley, Thomas, House |
| Smith, C. Harvey, House |
| Smith, Henry, House |
| Smith, Nathan, House |
| Snow, Arthur, House |
| Snyder Guard Station Historical District |
| Soda Springs City Hall |
| Soderling, Russell and Pearl, House |
| Sommercamp, Mary Elizabeth, House |
| Sommer, Morris, House |
| Soncarty, Edward and Ida, Barn |
| Sonner-Osier Farmstead Historic District |
| South Boise Fire Station |
| Southern Idaho Timber Protective Association (SITPA) Buildings |
| Southern Idaho Timber Protective Association (SITPA) Buildings |
| South Municipal Pool |
| Sparks, Walter, House |
| Spaulding, Almon W. and Dr. Mary E., Ranch |
| Spencer, Edward S., House and Garage and the Fred Nelson Barn |
| Spencer, George, House |
| Spencer Rock House |
| Spokane Valley Land and Water Company Canal |
| Spori, Jacob, Building |
| Spud Drive-In Theater |
| St. Agnes Catholic Church |
| St. Alphonsus' Hospital Nurses' Home and Heating Plant/Laundry |
| St. Andrew's Episcopal Church |
| Standrod Bank |
| Stanley Ranger Station |
| Star Camp |
| State Bank of Kamiah |
| State Bank of Kooskia |
| Stephan, Louis, House |
| Steunenberg, A. K., House |
| Stevens, Arnold, House |
| Stewart, A. H., House |
| Stickel, John, House |
| St. James' Episcopal Mission Church |
| St. John Lutheran Church |
| St. John's Church |
| St. John's Episcopal 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 |
| Stone and Log Building |
| Stone Building |
| St Paul Missionary Baptist Church |
| St. Paul's Episcopal Church |
| St. Paul's Rectory and Sisters' House |
| Stricker Store and Farm |
| Stucki, J. U., House and Outbuildings |
| Sugarloaf School |
| Sunnyside School |
| Sutton, John, House |
| Swanger Hall |
| Sweet Methodist Episcopal Church |
| Tamblyn, Agnes M., House |
| Taylor, Arthur, House |
| Taylor's Candy Factory |
| Telephone Company Bungalow |
| Thomason Rice Barn |
| Thompson, Gaylord, House |
| Thompson Mortuary Chapel |
| Three-Room House |
| Thunborg, Jacob and Cristina, House |
| Toana Freight Wagon Road Historic District |
| Tolleth House |
| Tooley, Don, House |
| Tourtellotte, John, Building |
| Treaty Rock |
| Trinity Episcopal Church |
| Troy Downtown Historic District |
| Troy Hospital |
| Tueller, Jacob, Sr., House |
| Turner Hotel |
| Turner, John G., House |
| Twin Falls Bank and Trust Company Building |
| Twin Falls Canal Company Building |
| Twin Falls Downtown Historic District |
| Twin Falls Milling and Elevator Company Warehouse |
| Twin Falls Original Townsite Residential Historic District |
| Twin Falls Warehouse Historic District |
| Twin Peaks Sports |
| Underwood Hotel |
| Union Block and Montandon Buildings |
| Union School |
| United Presbyterian Church |
| Upper Brownlee School |
| Upper Twin Lakes School |
| U.S. Post Office |
| US Post Office-Bonners Ferry 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-St. Anthony Main |
Data from United States Park Service and Wikidata
