All - Constructed - 1930–1939
| Sidaway Bridge |
| Silver City Woman's Club |
| Silver Creek Ranger Station |
| Silver Dome Ballroom, The |
| Silver Peak Lookout Complex |
| Simmons Island Beach House |
| Sinclaire, Reginald, House |
| Sinclair Service Station |
| Singletary-Reese-Robinson House |
| Sinnott Memorial Building No. 67 |
| Siuslaw River Bridge No. 01821 |
| Sixth Avenue Underpass |
| Skinny House |
| Smith Clinic |
| Smith, Edwin, House |
| Smith, Henry, Statue |
| Smith, Jay Dayton, House |
| Smith, Ray F. and Ethel, House |
| Smith-Taylor Cabin |
| Smoot Dairy Farmhouse |
| Snogo Snow Plow |
| Sofia Warehouse |
| Soldiers and Sailors Memorial Bridge |
| Sons of Italy Hall |
| Sons of San Patricio Monument |
| Sourdough Mountain Lookout |
| South Campground Amphitheater |
| South Dakota Department of Transportation Bridge No. 63-016-150 |
| South Dakota Department of Transportation Bridge No. 63-132-040 |
| Southeast Stone Arch Bridge - Lake Wabaunsee |
| South Entrance Sign |
| South Milwaukee Post Office |
| South Puyallup River Bridge |
| South Range Community Building |
| South Side Fire Station No. 3 |
| South Union Street-Boardman River Bridge |
| Southwestern Range and Sheep Breeding Laboratory Historic District |
| Spanish Fork High School Gymnasium |
| Spaulding School Gymnasium-Auditorium |
| Spiegel Office Building |
| Spokane, Portland and Seattle Railway Steam Locomotive |
| Spring Creek Tributary Bridge |
| Spring Garden School No. 2 |
| Spring Street Service Station |
| Springville High School Art Gallery |
| Sprunt, James D. and Frances, Cottage |
| Square 1500 |
| Squirrel Hollow County Park Historic District |
| Stamford Bridge |
| St. Andrews Creek Bridge |
| St. Andrew's Episcopal Church |
| Star Engraving Company Building |
| Starved Rock Lock and Dam Historic District |
| State Highway 3 Bridge at the Nueces River |
| State Highway 96 Bridge |
| State Park Supply Yard |
| Steinbeck, John, House |
| Stein, Earl, House |
| Stevens, I.W., Lakeside Cottage |
| Stevens, Wayland H. and Mamie Burt, House |
| St. Francis City Park |
| St. George Elementary School |
| Stigler School Gymnasium-Auditorium |
| Stillwater Bridge |
| Stillwell, Erle, House II |
| St. John's Episcopal Church |
| St. Louis-San Francisco Overpass |
| St. Luke AME Zion Church |
| St. Olaf Auditorium |
| Stone Avenue Underpass |
| St. Paul Women's City Club |
| St. Peter Cathedral |
| Strand Theatre |
| Stratton Mountain Lookout Tower |
| Strawbridge and Clothier Store |
| Stroud School, Old |
| Sts. Peter and Paul Church |
| Sturgeon Bay Bridge |
| Sturgeon Bay Post Office |
| Sugar Lake State Park Open Shelter |
| Sugarloaf Fire Tower Historic District |
| Sullivan House |
| Summerfield School Gymnasium and Community Center |
| Summerland Trail Shelter |
| Summers House |
| Sunbury High School |
| Sun Camp Fireguard Cabin |
| Sunnydale |
| Sunrise Comfort Station |
| Sunset Lodge |
| Sunset Park Historic District |
| Sunset Park Trail Shelter |
| Suntop Lookout |
| Sushana River Ranger Cabin No. 17 |
| Swann Covered Bridge |
| Swanson Boathouse |
| Swiftcurrent Fire Lookout |
| Swiftcurrent Ranger Station Historic District |
| Table Rock State Park Historic District |
| Taliesin West |
Data from United States Park Service and Wikidata
