I
- The ice that built the ground: the interlobate fans The Land
- Immigrant place-names as folklore, tested: the ground has theme names, not transfer names Famous Stories & the Record
- The imperial door: how a Canadian plant opened Empire trade — and the door this ground never had Exports
- The improvised-ingenuity class, tested: no boat graded a Granger street Famous Stories & the Record
- The Indiana State Library Sources
- “Indiana's oldest zoo,” tested — and the name course, with the 2025 date corrected Zoo
- The Indianapolis line in three distinct forms — test drivers, the builder who raced there, the home starter — all three South Bend's, none Granger's Racing
- The industrial buildings as architecture: Princess Way and Sandy Court — low sheds, one millwork plant, one brewery Architecture
- Industrial fame as a location: the Microsoft ground, and the headquarters that is not here Famous Landmarks
- Industrial Revolution Section
- Industry-defining inventions of Granger-seated firms — the tested negative Inventors & Inventions
- Influencers & Digital Creators Section
- The infrastructure winners: a carrier hotel in a train station, a fiber ring in traffic conduit Dot-Com Era
- Inside Granger: the years the Tribune built the suburb a magazine of its own Newspapers & Media
- The institutional production houses in succession: Golden Dome to Fighting Irish Media at the university across the line, and WNIT's own producers and programmes — with the no-campus line stated for this ground Film & TV Producers
- The institutional tables: a club dining room, a school basement, a parish feast Food & Drink
- The institutional test: no jail, no court, no workhouse has ever stood here Crime & Public Safety
- Institutions built: Hering House, the NAACP branch, and the Allens' thirty years of cases Black History
- "International" as a build: customs, the inspection station, and the Liverpool 747 Airports
- Into market: the first entries in the county were made on this ground The Land
- The invaders, named and gated: zebra mussels in the basin, carp at the gate and not through it Wildlife
- Invention claims, tested: no "invented here" — but the patent record seats inventors on this ground by the page Famous Stories & the Record
- Inventors & Inventions Section
- Investigators and organizations: who actually worked this sky, and what they filed UFO Sightings
- The Irvin thirteen: one Harris Township farm sends a squad to the 29th Indiana Wars & Military Service
- The Irvins: W. and E. M. in the settler roll, and the directory's two Irvin farms Notable People
- Isaac Shetterly: mason's trade and an 84-acre farm on the state line Notable People