Iowa - Significance region: Local
| St. Joseph's Roman Catholic Church and Cemetery Historic District |
| St. Katherine's Historic District |
| St. Lawrence Catholic Church |
| St. Luke's Hospital |
| St. Luke's Methodist Church |
| St. Luke's School and Recreation Center |
| St Mary of the Assumption Church |
| St. Mary's Academy |
| St. Mary's Catholic Church Historic District |
| St. Mary's Church and Rectory |
| St. Mary's Parish Church Buildings |
| St. Mary's Rectory |
| St. Mary’s Roman Catholic Church |
| St. Mary's Roman Catholic Church Complex |
| St. Matthew's by the Bridge Episcopal Church |
| St. Michael's Church, Cemetery, Rectory and Ancient Order of Hibernians Hall |
| Stock Judging Pavilion |
| Stokes, Dr. Ella, House |
| St. Olaf Auditorium |
| Stoll Building Works |
| Stone Academy |
| Stone House |
| Stoner, Thomas I., House |
| Stone School |
| Storm Lake High School |
| St. Patrick Church |
| St. Patrick's Catholic Church, Cedar |
| St. Patrick's Church |
| St. Patrick's Church-Garryowen |
| St. Paul's English Lutheran Church |
| St. Paul's Episcopal Church |
| St. Paul's Episcopal Church and Parish Hall |
| St. Peter Church |
| St. Peter's Church and Rectory |
| St. Peters United Evangelical Lutheran Church |
| Stranahan, Prof. Edgar H. and Irene D., House |
| Stratton House |
| Stringtown House |
| Struck, Dr. Kuno, House |
| St. Stephen's Episcopal Church |
| St. Thomas Episcopal Church |
| Stuart, Dr. Richard and Paulina, House |
| Stubbins, George E., House |
| Stuckslager, Harrison, House |
| Studebaker Corporation Branch Office Building |
| Sturdevant Southwest Historic District |
| Sturdivant-Sawyer House |
| Suiter, Jacob, House |
| Suiter, John H., House |
| Suiter, William, House |
| Summit Apartment Building |
| Sumner High School |
| Sumner School |
| Swan, George B., House |
| Swedesburg Historic Commercial District |
| Swedish Baptist Church |
| Swedish Evangelical Lutheran Augustana Church |
| Swedish Evangelical Lutheran Church |
| Swigert, W. B., House |
| Sylvan Theater Historic District |
| Syndicate Block |
| Syndicate Block |
| Tabor Antislavery Historic District |
| Tabor Congregational Church |
| Taft, Stephen Harris, House |
| Taft-West Warehouse |
| Tama County Courthouse |
| Tama County Jail |
| Tastee-Freez Drive In and Dairy Store |
| Tate Arms |
| Taubman, Henry, House |
| Taylor County Courthouse |
| Taylor School |
| Taylor-Van Note |
| Taylor, Wenzil, Building |
| Teachout Building |
| Tedford, W. H., House |
| Temple, Marcellus Luther and Julia Protzman, House |
| Templeton, I. Edward, House |
| Ten Hagen Cottage-Stegman Store |
| Terrace Park Historic District |
| Tevoet, Lambert, House |
| The Capitol Theater |
| Thedinga, J. H., House |
| Theodore Roosevelt High School |
| The Park Place-Grand Avenue Residential District |
| Third Street Bridge (FHWA No. 012250) |
| Thompson, Charles J., House |
| Tidrick, Miller Richard and Mary Fisher, House |
| Timmerman-Burd Building |
| Tipton State Bank |
| Torrance House |
| Town Clock Building |
| Trent-Beaver House |
| Trimble-Parker Historic Farmstead District |
| Trinity Episcopal Church |
| Trinity Episcopal Church |
| Trinity Memorial Episcopal Church |
| Trinity Methodist Episcopal Church |
| Tromley, George, Jr., House |
Data from United States Park Service and Wikidata
