I
- ice cream parlors (2)
- ice industry (4)
- ice skating rinks (1)
- icebreakers (1)
- icehouses (19)
- immigrants (73)
- incinerators (5)
- inclined planes (5)
- Indian reservations (1)
- Indiana limestone (1)
- Indians of North America (159)
- indigenous peoples (7)
- industrial facilities (121)
- industrial towns (1)
- industrial works (1)
- industry (1053)
- infirmaries (5)
- inspection (4)
- institutional care (1)
- insurance (2)
- intakes (9)
- intelligence (1)
- interlocking towers (1)
- international relations (2)
- International Style architectural elements (4)
- interpretation (1)
- Ionic order (2)
- iron fences (7)
- iron industry (77)
- iron truss bridges (35)
- ironworks (17)
- ironwork (19)
- irrigation canals (45)
- irrigation (52)
- islands (247)
- Italianate architectural elements (8)