Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Trenton | Populated Place | 275 | Blackford | 40 27 00 N | 085 14 20 W |
| Trevlac | Populated Place | 195 | Brown | 39 15 56 N | 086 20 13 W |
| Tri Brook | Stream | | Posey | 38 01 09 N | 087 52 16 W |
| Tri Central Junior-Senior High School | School | 266 | Tipton | 40 22 31 N | 086 03 13 W |
| Tri Junior-Senior High School | School | 341 | Henry | 39 50 00 N | 085 19 60 W |
| Tri Run | Stream | | Jay | 40 30 26 N | 084 57 32 W |
| Tri State Airport | Airport | 252 | Marshall | 41 19 26 N | 086 11 53 W |
| Tri-City Plaza Shopping Center | Locale | 181 | Lake | 41 36 00 N | 087 23 29 W |
| Tri-County Community Church | Church | 242 | Putnam | 39 33 15 N | 086 40 27 W |
| Tri-County State Fish And Game Area | Park | 264 | Kosciusko | 41 21 32 N | 085 39 57 W |
| Tri-County West Elementary School | School | 223 | White | 40 45 45 N | 087 08 48 W |
| Tri-Lakes | Populated Place | 286 | Whitley | 41 14 45 N | 085 26 31 W |
| Tri-Lakes Chapel | Church | 239 | Elkhart | 41 45 25 N | 085 49 43 W |
| Tri-Land Estates Lake | Reservoir | 166 | Vigo | 39 29 42 N | 087 27 54 W |
| Tri-Land Estates Lake Dam | Dam | 166 | Vigo | 39 29 42 N | 087 27 54 W |
| Tri-State Steuben County Airport | Airport | 299 | Steuben | 41 38 22 N | 085 05 12 W |
| Tri-State University | School | 322 | Steuben | 41 37 57 N | 085 00 15 W |
| Tri-West High School | School | 292 | Hendricks | 39 53 13 N | 086 32 33 W |
| Tri-West Junior High School | School | 292 | Hendricks | 39 53 13 N | 086 32 33 W |
| Triangle School | School | 238 | Shelby | 39 31 53 N | 085 45 33 W |
| Tributary Number One | Canal | 259 | Howard | 40 24 53 N | 085 58 41 W |
| Tributary Number Two | Canal | 259 | Howard | 40 25 27 N | 085 56 27 W |
| Tricker Cemetery | Cemetery | 249 | Adams | 40 42 31 N | 084 50 22 W |
| Trigger Branch | Stream | | Perry | 38 00 43 N | 086 34 12 W |
| Trilobi Hills | Populated Place | 252 | Marion | 39 52 45 N | 085 59 48 W |
| Trimble Cemetery | Cemetery | 219 | Orange | 38 37 06 N | 086 19 54 W |
| Trimble Cemetery | Cemetery | 156 | Sullivan | 38 58 37 N | 087 19 49 W |
| Trimble Creek | Stream | | Kosciusko | 41 07 49 N | 085 52 11 W |
| Trimble Ditch | Canal | 264 | Tipton | 40 20 16 N | 085 54 58 W |
| Trimmer Hill | Summit | 189 | Vigo | 39 21 02 N | 087 18 07 W |
| Trimnell Branch | Stream | | Bartholomew | 39 20 13 N | 085 50 24 W |
| Trinity | Populated Place | 263 | Jay | 40 32 33 N | 084 50 55 W |
| Trinity Baptist Church | Church | 219 | Marion | 39 48 45 N | 086 07 36 W |
| Trinity Cemetery | Cemetery | 317 | Steuben | 41 35 06 N | 085 06 33 W |
| Trinity Christian Methodist Episcopal Church | Church | 220 | Marion | 39 47 58 N | 086 08 06 W |
| Trinity Church | Church | 207 | Bartholomew | 39 12 40 N | 085 47 27 W |
| Trinity Church | Church | 267 | DeKalb | 41 22 56 N | 085 03 16 W |
| Trinity Church | Church | 230 | Elkhart | 41 41 17 N | 085 56 11 W |
| Trinity Church | Church | 222 | Elkhart | 41 40 36 N | 085 59 53 W |
| Trinity Church | Church | 144 | Floyd | 38 19 33 N | 085 48 00 W |
| Trinity Church | Church | 299 | Franklin | 39 21 02 N | 085 00 11 W |
| Trinity Church | Church | 142 | Knox | 38 37 12 N | 087 28 33 W |
| Trinity Church | Church | 226 | Lawrence | 38 49 56 N | 086 26 10 W |
| Trinity Church | Church | 292 | Noble | 41 24 09 N | 085 25 25 W |
| Trinity Church | Church | 151 | Spencer | 38 05 59 N | 086 49 45 W |
| Trinity Church | Church | 168 | Vigo | 39 36 00 N | 087 26 42 W |
| Trinity Church | Church | 164 | Wayne | 38 20 30 N | 085 39 22 W |
| Trinity Church of God | Church | 183 | Lake | 41 34 24 N | 087 21 09 W |
| Trinity Episcopal Church | Church | 221 | Marion | 39 48 54 N | 086 09 21 W |
| Trinity Evangelical Lutheran Church | Church | 182 | Lake | 41 34 59 N | 087 31 15 W |
| Trinity Evangelical Lutheran Church | Church | 223 | Lake | 41 24 50 N | 087 21 12 W |
| Trinity Evangelical Lutheran Church (historical) | Church | 187 | Lake | 41 32 00 N | 087 15 21 W |
| Trinity Evangelical Lutheran School | School | 223 | Lake | 41 24 50 N | 087 21 12 W |
| Trinity Free Methodist Church | Church | 207 | Lake | 41 27 37 N | 087 15 36 W |
| Trinity Lutheran Church | Church | 217 | Lake | 41 17 23 N | 087 26 06 W |
| Trinity Lutheran Church | Church | 191 | Lake | 41 31 26 N | 087 14 49 W |
| Trinity Lutheran Church | Church | 265 | Marion | 39 47 25 N | 086 01 01 W |
| Trinity Lutheran Church | Church | 237 | Porter | 41 28 12 N | 087 03 40 W |
| Trinity Lutheran Church (historical) | Church | 184 | Lake | 41 35 49 N | 087 20 09 W |
| Trinity Lutheran School | School | 238 | Allen | 41 05 23 N | 085 09 21 W |
| Trinity Lutheran School | School | 191 | Lake | 41 31 26 N | 087 14 56 W |
| Trinity Lutheran School | School | 266 | Marion | 39 47 26 N | 086 01 01 W |
| Trinity Lutheran School | School | 117 | Vanderburgh | 37 58 45 N | 087 34 42 W |
| Trinity Missionary Baptist Church | Church | 186 | Lake | 41 35 03 N | 087 19 46 W |
| Trinity Parish Cemetery | Cemetery | 146 | Vanderburgh | 38 08 41 N | 087 31 38 W |
| Trinity Presbyterian Church | Church | 244 | Marion | 39 54 43 N | 086 09 04 W |
| Trinity Reformed Church | Church | 189 | Lake | 41 33 40 N | 087 29 57 W |
| Trinity Run | Stream | | Floyd | 38 18 33 N | 085 49 58 W |
| Trinity School | School | 243 | Allen | 41 00 49 N | 085 06 31 W |
| Trinity School | School | 117 | Posey | 37 58 45 N | 087 34 43 W |
| Trinity Springs | Spring | 183 | Martin | 38 45 26 N | 086 45 52 W |
| Trinity Springs | Spring | 146 | Martin | 38 45 27 N | 086 45 21 W |
| Trinity Temple Church | Church | 264 | Howard | 40 24 48 N | 086 07 42 W |
| Trinity United Methodist Church | Church | 192 | Lake | 41 33 51 N | 087 14 51 W |
| Trinity Wesleyan Church | Church | 227 | Marion | 39 50 23 N | 086 07 50 W |
| Triple Lakes | Lake | 218 | Franklin | 39 26 42 N | 085 11 18 W |
| Trippet Cemetery | Cemetery | 153 | Gibson | 38 26 23 N | 087 31 53 W |
| Trippet Ditch | Canal | 125 | Gibson | 38 25 07 N | 087 31 16 W |
| Triton Central High School | School | 244 | Shelby | 39 36 42 N | 085 52 25 W |
| Trittipo Ditch | Canal | 257 | Marion | 39 52 45 N | 085 56 34 W |
| Triumph Church | Church | 288 | Jay | 40 22 23 N | 085 12 17 W |
| Triumph Holiness Church | Church | 220 | Marion | 39 47 30 N | 086 07 55 W |
| Trotter Creek | Stream | | Morgan | 39 37 48 N | 086 19 39 W |
| Trotter Crossing | Populated Place | 223 | Orange | 38 30 41 N | 086 21 56 W |
| Trout Cemetery | Cemetery | 249 | Harrison | 38 12 29 N | 086 12 21 W |
| Trout Creek | Stream | | Elkhart | 41 44 57 N | 085 48 21 W |
| Trout Creek Cemetery | Cemetery | 234 | Elkhart | 41 45 13 N | 085 48 57 W |
| Trouthaven Lake | Lake | 226 | Lake | 41 25 02 N | 087 13 30 W |
| Troutman Branch | Stream | | Parke | 39 44 55 N | 087 04 42 W |
| Troutman Hogan Ditch | Canal | 230 | Fulton | 41 00 28 N | 086 27 07 W |
| Troxel Lake | Lake | 270 | LaGrange | 41 42 40 N | 085 21 12 W |
| Troy | Populated Place | 144 | Perry | 37 59 43 N | 086 47 52 W |
| Troy Cedar Lake | Lake | 276 | Whitley | 41 14 22 N | 085 34 41 W |
| Troy Church | Church | 287 | Whitley | 41 13 19 N | 085 36 54 W |
| Troy Church | Church | 283 | Whitley | 41 13 55 N | 085 34 40 W |
| Truax Ditch | Canal | 253 | Kosciusko | 41 21 56 N | 085 55 06 W |
| Truax Hill | Summit | 244 | Montgomery | 39 59 48 N | 087 03 14 W |
| True Belief Baptist Church | Church | 218 | Marion | 39 48 10 N | 086 08 58 W |
| True Light Baptist Church | Church | 222 | Marion | 39 47 52 N | 086 08 19 W |
| True Light Fellowship Church | Church | 196 | Lake | 41 32 11 N | 087 19 43 W |
| True Spiritual Church | Church | 215 | Marion | 39 46 00 N | 086 11 52 W |
| Truelove Church | Church | 189 | Martin | 38 34 38 N | 086 54 01 W |
| Truesdale Ditch | Canal | 259 | LaGrange | 41 42 46 N | 085 35 44 W |
| Truitt Cemetery | Cemetery | 304 | Delaware | 40 10 18 N | 085 17 21 W |
| Truitt Ditch | Stream | | Delaware | 40 11 25 N | 085 21 20 W |
| Try Run | Stream | | Clark | 38 30 06 N | 085 46 44 W |
| Tryus Church | Church | 226 | Gibson | 38 37 15 N | 085 30 56 W |
| Tub Creek | Stream | | Ripley | 39 15 18 N | 085 18 17 W |
| Tucker Cemetery | Cemetery | 226 | Johnson | 39 25 04 N | 086 04 00 W |
| Tucker Cemetery | Cemetery | 271 | Tipton | 40 16 23 N | 086 07 40 W |