Iowa - Significance region: Local
| Robinson, George W. and Mary J. (Maxwell), House |
| Rockford Mill |
| Rock Island Passenger Depot |
| Rogers-Knutson House |
| Roling, Henry, House |
| Romey, George, House |
| Roosevelt Elementary School |
| Roosevelt School |
| Rose Hill |
| Rose Hill Historic District |
| Rose Hill Methodist Episcopal Church |
| Roshek Brothers Department Store |
| Roslyn Flats |
| Ross Grain Elevator |
| Rowhouses at 702-712 Kirkwood Boulevard |
| Royal Neighbors of America National Home Historic District |
| Ruan Center & Carriers Building |
| Rule, Duncan, House |
| Russell, Chuck and Emily, House |
| Russell, Rensselaer, House |
| Rye, Chris, House |
| Sac City Chicago and North Western Depot |
| Sac City Monument Square Historic District |
| Sac County Courthouse |
| Sacred Heart Catholic Church |
| Sacred Heart Hospital |
| Sacred Heart Roman Catholic Cathedral Complex |
| Sacred Heart School |
| Saengerfest Halle |
| Saint Ansgar Public School |
| Saint Barnabas Episcopal Church |
| Saint Boniface Catholic Church District |
| Saint Boniface Church |
| Saint Irenaeus Church |
| Saint John's Roman Catholic Church |
| Saint Patrick's Catholic Church and Rectory |
| Saint Patrick's Roman Catholic Church |
| Saints Peter and Paul Catholic Church |
| Saints Peter and Paul Catholic Church |
| Saints Peter and Paul Church |
| Saints Peter and Paul Roman Catholic Church Historic District |
| Sample, Hugh W. and Sarah, House |
| Sanborn, C. M., Building |
| Sandwich-Marseilles Manufacturing Building |
| Sanford, Arthur and Stella, House |
| Sankot Motor Company |
| Sargent's Garage |
| Sauser-Lane House |
| Savery Hotel |
| Schantz, Christian K. and Margaret (Rich), House and Carpentry Shop |
| Schebler, Richard, House |
| Scheibe, Julius, Cottage |
| Schindhelm-Drews House |
| Schlapp, George E., House |
| Schmidt Block |
| Schmidt, F. Jacob, House |
| Schmidt House |
| Schmidt, Louis C. and Amelia L., House |
| Schmitt and Henry Manufacturing Company |
| Schnellbacher, John and Fredericka Meyer, House |
| Schoenenberger, Nicholas, House and Barn |
| School Number 6 |
| Schramm Building |
| Schricker, John C., House |
| Schricker, John, House |
| Schroeder Bros, Meat Market |
| Schroeder-Klein Grocery Company Warehouse |
| Schrup, John and Marie (Palen) Farmstead Historic District |
| Schulein, Ben and Harriet, House |
| Schultz Brothers Drug Store |
| Sciola Missionary Baptist Church |
| Scotch Grove Historic District |
| Scott County Jail |
| Scottish Rite Consistory Building |
| Scott, Mary A. and Caleb D., House |
| Seaman, Roy C. and Lena (Johnson), House |
| Second and Third Avenue Historic District |
| Second Baptist Church |
| Second Baptist Church |
| Security Building |
| Security Building |
| Seeberger-Loring-Kilburn House |
| Seerley, William and Mary (Messersmith) Barn and Milkhouse-Smokehouse |
| Seminary Hill Residential Historic District |
| Seminole Valley Farmstead |
| Sentinel Block |
| Seth Richards Commercial Block |
| Seven Oaks |
| Severson, Nels, Barn |
| Sexton Hotel |
| Shantz, Martin L. and Mary Jane (Yount), House |
| Sharon Cemetery Historic District |
| Sharon, Fred B., House |
| Sharon Methodist Episcopal Church |
| Shaw, Col. William T. and Elizabeth C., House |
| Shaw, E. A., House |
| Shay, Lee, Farmhouse |
| Sheaffer, Craig and Virginia, House |
| Shea, John J. and Agnes, House |
| Shelby Consolidated School |
Data from United States Park Service and Wikidata
