Iowa - Criteria: C (architecture/engineering)
| Hebert, Louis, House |
| Hedge Block |
| Heinz, Bonaventura, House (second) |
| Henderson, Daniel and Nancy Swaford, House |
| Henne, Robert, House |
| Henn Mansion |
| Henry County Courthouse |
| Henry County Savings Bank |
| Henryson, Henry T. and Emilie (Wiese), House |
| Henshie-Briggs Row House |
| Henyon-Kasper-Duffy Barn |
| Heritage Hill Historic District |
| Herman, John H., House |
| Herndon Hall |
| Herring Motor Car Company Building |
| Herrold Bridge |
| Herschel-Spillman Two-Row Portable Menagerie Carousel |
| Herschler, Christian and Katharina, House, Barn and Outbuildings Historic District |
| Hibernia Hall |
| Highland Historic District |
| Highland Park Historic Business District at Euclid and Sixth Avenues |
| Highlandville School |
| Highwater Rock |
| Hiller Building |
| Hillside |
| Hippee Building |
| Historic Railroad District |
| Hitchcock, Rev. George B., House |
| Hoag, J. J., House |
| Hobson Block |
| Hoersch, John, House |
| Hoffman Building |
| Hoffman, Phil, House |
| Hoffman, Samuel, Jr., House |
| Hofmann Building |
| Hogback Covered Bridge |
| Hohberger Building |
| Holbrook, William, House |
| Holdoegel, Perry C. and Mattie Forrest, House |
| Holland, Ora, House |
| Hollenfelz House |
| Holliwell Covered Bridge |
| Holmes, John S. and Elizabeth Beem, Barn |
| Holtkamp Round Barn |
| Holy Ghost Catholic Historic District |
| Holy Trinity Greek Orthodox Church |
| Home Federal Savings and Loan Association of Des Moines Building |
| Homestead Building |
| Honey Creek Friends' Meetinghouse |
| Hope Fire Company Engine House |
| Hornback, Emily, House |
| Horn House |
| Hose Station No. 1 |
| Hose Station No. 6 |
| Hose Station No. 7 |
| Hotel Burlington |
| Hotel Charitone |
| Hotel Chieftain |
| Hotel Fort Des Moines |
| Hotel Hurst |
| Hotel Hurst Garage |
| Hotel Iowa |
| Hotel Kirkwood |
| Hotel Manning |
| Hotel Mealey |
| Hotel Mississippi-RKO Orpheum Theater |
| Hotel Ottumwa |
| Hotel President |
| Hotel Randolph |
| Hotel Roosevelt |
| House at 111 E. Maple Street |
| House at 1646 W. Second Street |
| House at 2123 W. Second Street |
| House at 2212 W. River Drive |
| House at 318-332 Marquette Street |
| House at 505 Court Street |
| House at 919 Oneida Street |
| Howard County Courthouse |
| Hubbell Warehouse |
| Hughes, David and M. Maria, House |
| Hughes-Irons Motor Company |
| Hughes, Martin, House |
| Hult, Charles E., House, Summer Kitchen and Wood Shed |
| Humboldt County Court House |
| Humboldt Free Public Library |
| Hunter School |
| Hurst, A. A., House |
| IANR Railroad Underpass |
| Ida County Courthouse |
| Illinois Central Combination Depot-Ackley |
| Illinois Central Passenger Depot-Storm Lake |
| Illinois Central Railroad Yard-Cherokee |
| Imes Covered Bridge |
| Immanuel Danish Evangelical Lutheran Church |
| Indian Creek Bridge |
| Indianola Carnegie Library |
| Indianola High School |
| Ingemann Danish Evangelical Lutheran Church and Cemetery |
| Ingersoll Place Plat Historic District |
| Insane Asylum at the County Poor Farm |
Data from United States Park Service and Wikidata
