Iowa - Significance region: Local
| Shelby County Courthouse |
| Sheldahl First Norwegian Evangelical Lutheran Church |
| Shellito, Dr. Judd C. and Margaret S. Clarke, House |
| Sherman Hill Historic District |
| Sherman, Hoyt, Place |
| Sherman, Lampson P., House |
| Sherman Nursery Company Historic District |
| Shields Woolen Mill |
| Shoemake, John H., House |
| Shores-Mueller Company |
| Shriver, William R. and Martha Foster, House |
| Siebels' Department Store-Boyer Valley Bank |
| Sieben, Mrs. Margaret, House |
| Siemer House |
| Sigma Pi Fraternity House |
| Sigma Sigma-Delta Chi Fraternity House |
| Simmons Hardware Company Warehouse |
| Simmons, John P., House |
| Simpson, Charles S., House |
| Sinclair Building-Smulekoffs Furniture Store |
| Singmaster, C.F. and Mary, House |
| Sioux City Central High School |
| Sioux City Fire Station Number 3 |
| Sioux City Free Public Library |
| Sioux City Linseed Oil Works |
| Sioux City Masonic Temple |
| Sioux City Public Library-North Side Branch |
| Sioux Theatre |
| Sitz, Rudolph H., Building |
| Sixth and Forest Historic District |
| Slye, Thomas, House |
| Smith, Alvord I., House |
| Smith Farmhouse |
| Smith, Gen. Cass and Belle, House |
| Smith, Henry H./J.H. Murphy House |
| Smith, Hiram C., House |
| Smith, Hiram C., Milking Shed |
| Smith, James, House |
| Smith, James J. and Anna J. (Linean), House #1 |
| Smith, James J. and Anna J. (Linean), House #2 |
| Smith, John, House |
| Smith-Johnson House |
| Smith, Peter and Mary, House |
| Smith, William G., House |
| Smouse, David W., Opportunity School |
| Smouse, Winfield, House |
| Snake Alley |
| Snake Alley Historic District |
| Snowden House |
| Sokol Gymnasium |
| South 8th Street Historic District |
| Southeast Water Trough |
| South Summit Street District |
| Spaulding Manufacturing Company |
| Spencer, Charles H., House |
| Spencer High School and Auditorium |
| Spencer, Roswell, House |
| Spirit Lake Public Library |
| Sprague, Brown, and Knowlton Store |
| Spring Creek Friends Cemetery |
| Spring Creek Meeting House-H Street Mission |
| Spring Side |
| Spurgin Residence |
| Squiers, J. E., House |
| St. Ambrose Cathedral and Rectory |
| Standard Glass and Paint Company Building |
| St. Anthony’s Church |
| St. Anthony's Roman Catholic Church Complex |
| Star-Clipper-Canfield Building and Winding Stairway |
| Starker-Leopold Historic District |
| State Bank of Stratford |
| State Center Commercial Historic District |
| State Savings Bank |
| State Savings Bank |
| State Savings Bank |
| Stauer, Peter, House |
| St. Boniface Catholic Church |
| St. Boniface Historic District |
| St. Boniface of New Vienna Historic District |
| Steamboat Rock Consolidated Schools Building |
| Stearns, C. S., House |
| Stemmer, J. C., House |
| Stephens, A. J., House |
| Stevenson, Samuel A. and Margaret, House |
| Stewart, Frank, House |
| Stewart, J. W., House |
| Stewart Library |
| Steyer Bridge |
| Steyer Opera House |
| St. George's Episcopal Church |
| St. James Episcopal Church |
| St. James United Methodist Church |
| St. John Baptist Church |
| St. John's Danish Evangelical Lutheran Church Historic District |
| St. John's Episcopal Church and Parish Hall |
| St. John's Lutheran Church |
| St. John's Methodist Episcopal Church |
| St. Joseph Hospital Historic District |
| St. Joseph's Catholic Church |
| St. Joseph's Roman Catholic Church |
Data from United States Park Service and Wikidata
