Iowa - Area of significance: Agriculture
| Seminole Valley Farmstead |
| Singmaster, C.F. and Mary, House |
| Slayton Farms-Round Barn |
| Spotts Round Barn |
| Thomsen Round Barn |
| Tonsfeldt Round Barn |
| Trimble-Parker Historic Farmstead District |
| Tyden Farm No. 6 Farmstead Historic District |
| Vander Wilt Farmstead Historic District |
| Vermeer, Gary J. and Matilda, Farmstead |
| Vermilion Estate |
| Wallace, Henry C., House |
| Wallace, Henry, House |
| Waveland Round Barn |
| Weis, Henry, House |
| Wickfield Round Barn |
| Wood, Herman, Round Barn |
| Young, John W., Round Barn |
Data from United States Park Service and Wikidata
