Iowa - Area of significance: Engineering
| 280th Street Bridge |
| Adair Viaduct |
| Adel Bridge |
| Albright Bridge |
| Alden Bridge |
| Ames Creek Bridge |
| Ashton, Ned, House |
| Beaver Creek Bridge |
| Beaver Creek Bridge |
| Bellefountain Bridge |
| Berkhimer Bridge |
| Bertram Bridge |
| Best, Louis P. and Clara K., Residence and Auto House |
| Big Creek Bridge |
| Big Creek Bridge 2 |
| Big Slough Creek Bridge |
| Boone Bridge 2 |
| Boone River Bridge |
| Boone Viaduct |
| Bridge near West Liberty |
| Bridgeport Bridge |
| Brooke Creek Bridge |
| Brooks Round Barn |
| Buck Grove Bridge |
| Burlington Railroad Overpass |
| Calamus Creek Bridge |
| Camp Dodge Pool District |
| Carpenter, James Sansom, House |
| Cascade Bridge |
| Chain Lakes Bridge |
| Chambers Ford Bridge |
| Cherry Street Bridge |
| Chicago, Rock Island and Pacific Railroad Stone Arch Viaduct |
| Clark Round Barn |
| CM and StP Railroad Underpass |
| Coal Creek Bridge |
| Cornelia Lake Bridge |
| County Line Bridge |
| Court Avenue Bridge |
| Cunningham Bridge |
| Curtis, Gen. Samuel R., House |
| Cutler-Donahue Covered Bridge |
| Des Moines River Bridge |
| Dexter Community House |
| Dillon Memorial |
| Dobbin Round Barn |
| Dry Run Bridge |
| Dunkerton Bridge |
| Dunleith and Dubuque Bridge |
| Dyas Hexagonal Barn |
| East Indian Creek Bridge |
| Eckle Round Barn |
| Eisenhower Bridge |
| Eldorado Bridge |
| Elkader Keystone Bridge |
| Ellsworth Ranch Bridge |
| Ely's Stone Bridge |
| Eveland Bridge |
| First Avenue Bridge |
| Fish Creek Bridge |
| Fobes Octagon Barn |
| Fort Atkinson Bridge |
| Fort Madison Bridge |
| Frantz Round Barn |
| Fremont Mill Bridge |
| Garnavillo Township Bridge |
| Garnavillo Township Culvert |
| Garretson Outlet Bridge |
| GEO. M. VERITY |
| Gilliece Bridge |
| Gipple's Quarry Bridge |
| Grand River Bridge |
| Grand River Bridge |
| Great Northern Railway Steam Locomotive No. 1355 and Tender 1451 |
| Grimes Octagon Barn |
| Guttenberg Corn Canning Co. |
| Hale Bridge |
| Hammond Bridge |
| Haner, William, Polygonal Barn |
| Harvey Railroad Bridge |
| Hawkeye Creek Bridge |
| Hawkeye Street Underpass |
| Hazen, Allen, Water Tower |
| Herrold Bridge |
| Herschel-Spillman Two-Row Portable Menagerie Carousel |
| Hogback Covered Bridge |
| Holliwell Covered Bridge |
| Holtkamp Round Barn |
| Hotel Randolph |
| IANR Railroad Underpass |
| Imes Covered Bridge |
| Indian Creek Bridge |
| Iowa Building |
| Iowa Falls Bridge |
| Jefferson Street Viaduct |
| Julien Dubuque Bridge |
| Keigley Branch Bridge |
| Keokuk Lock and Dam |
| Kilbourn Bridge |
| Kittyhawk Avenue Bridge |
Data from United States Park Service and Wikidata
