- Insular Affairs Division58
- Insular Affairs, Bureau1
- Insular Affairs, Bureau of29
- Insular Commission1
- Insular Purchasing Agent, Bureau of the1
- Interior, Department of the1
- Internal Revenue Commissioner3
- International Waterways Commission7
- Irrigation and Reclamation Committee, House1
- Isthmian Canal Commission2
- Isthmian Canal Commission, 1904-207
- Judge Advocate General23
- Judge Advocate General's Department161
- Judiciary Committee, House5
- Justice, Bureau of1
- Laboratories, Government, Bureau of28
- Lakes, Department of the3
- Library21
- Lighthouses Bureau4
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