- Great Britain. War Office. Topographical Depot3
- Greenough, George Bellas, 1778-18553
- Guilmin, L3
- Gunnison, J. W. (John Williams), 1812-18533
- Hansen, Michael C.3
- Hefel, Toney C., cartographer.3
- Hogberg, Rudolph K.3
- Hole, Allen David, 1866-19403
- Howell, Reading, 1743-18273
- Hôtel Karersee3
- Hull, Dennis N.3
- Hutchins, Thomas, 1730-17893
- Illinois. Railroad and Warehouse Commission3
- International Joint Commission3
- Iowa Geological Survey3
- Iowa. Board of Railroad Commissioners3
- Iowa. Board of Railroad Commissioners.3
- Iowa. Highway Commission3
- Iowa. State Planning Board. Recreation & Historic Division3
- Irvine, William, 1741-18043