Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Trinity School | School | 346 | Boone | 42 04 03 N | 093 52 57 W |
| Trinity School | School | 180 | Clinton | 41 50 34 N | 090 11 32 W |
| Trinity School | School | 239 | Linn | 41 58 10 N | 091 41 23 W |
| Trinity School | School | 208 | Scott | 41 32 46 N | 090 35 23 W |
| Trinity Temple Church | Church | 282 | Polk | 41 37 50 N | 093 40 18 W |
| Trinity United Church of Christ | Church | 442 | O'Brien | 43 10 58 N | 095 28 15 W |
| Trinity United Methodist Church | Church | 287 | Bremer | 42 43 34 N | 092 29 18 W |
| Trinity United Methodist Church | Church | 305 | Buchanan | 42 37 12 N | 091 54 15 W |
| Trinity United Methodist Church | Church | 358 | Clayton | 42 38 40 N | 091 24 06 W |
| Trinity United Methodist Church | Church | 219 | Clinton | 41 51 31 N | 090 13 23 W |
| Trinity United Methodist Church | Church | 307 | Floyd | 43 04 09 N | 092 40 27 W |
| Trinity United Methodist Church | Church | 199 | Lee | 40 24 48 N | 091 23 43 W |
| Trinity United Methodist Church | Church | 224 | Linn | 41 58 24 N | 091 40 36 W |
| Trinity United Methodist Church | Church | 292 | Monroe | 41 01 39 N | 092 47 41 W |
| Trinity United Methodist Church | Church | 268 | Polk | 41 36 26 N | 093 37 42 W |
| Trinity United Methodist Church | Church | 302 | Pottawattamie | 41 15 15 N | 095 51 02 W |
| Trinity United Methodist Church | Church | 312 | Story | 41 53 58 N | 093 36 23 W |
| Trinity United Methodist Church | Church | 338 | Webster | 42 30 55 N | 094 09 53 W |
| Trinity United Presbyterian Church | Church | 295 | Warren | 41 21 32 N | 093 33 39 W |
| Trinity Wesleyan Church | Church | 268 | Black Hawk | 42 30 19 N | 092 26 44 W |
| Trinity Wesleyan Church | Church | 250 | Black Hawk | 42 18 42 N | 092 11 17 W |
| Trinity Womens Health Center | Hospital | 208 | Scott | 41 33 33 N | 090 35 20 W |
| Trinity Womens Health Center | Hospital | 198 | Scott | 41 32 44 N | 090 30 15 W |
| Trinkle Creek | Stream | | Crawford | 42 10 43 N | 095 13 45 W |
| Triple J Airport | Airport | 310 | Grundy | 42 27 30 N | 092 43 21 W |
| Triple S Exotic Animal Park | Locale | 353 | Ringgold | 40 46 10 N | 094 13 21 W |
| Tripoli | Populated Place | 314 | Bremer | 42 48 29 N | 092 15 30 W |
| Tripoli (historical) | Locale | 308 | Bremer | 42 48 34 N | 092 15 22 W |
| Tripoli City Hall | Building | 320 | Bremer | 42 48 45 N | 092 15 31 W |
| Tripoli Community School | School | 321 | Bremer | 42 48 04 N | 092 15 37 W |
| Tripoli Fire Station | Building | 312 | Bremer | 42 48 28 N | 092 15 19 W |
| Tripoli Library | Building | 313 | Bremer | 42 48 30 N | 092 15 31 W |
| Tripoli Nursing Home | Hospital | 320 | Bremer | 42 48 14 N | 092 15 44 W |
| Tripoli Police Department | Building | 313 | Bremer | 42 48 30 N | 092 15 31 W |
| Tripoli Post Office | Post Office | 313 | Bremer | 42 48 30 N | 092 15 31 W |
| Tripoli Recreation Center | Building | 313 | Bremer | 42 48 30 N | 092 15 31 W |
| Triumph School | School | 303 | Buchanan | 42 34 34 N | 092 00 49 W |
| Triumphant Church | Church | 304 | Webster | 42 29 41 N | 094 11 30 W |
| Triumphant Family Church | Church | 258 | Black Hawk | 42 26 60 N | 092 18 06 W |
| Troublesome Creek | Stream | | Cass | 41 25 11 N | 095 01 04 W |
| Troublesome Creek | Stream | | Keokuk | 41 18 02 N | 092 12 05 W |
| Troublesome Creek | Stream | | Keokuk | 41 24 16 N | 092 05 60 W |
| Troublesome Creek Wildlife Area | Park | 374 | Cass | 41 29 10 N | 094 51 23 W |
| Trout Creek | Stream | | Winneshiek | 43 16 45 N | 091 46 29 W |
| Trout Creek | Stream | | Winneshiek | 43 17 29 N | 091 40 34 W |
| Trout River | Stream | | Winneshiek | 43 19 07 N | 091 40 17 W |
| Trout River Access Area | Locale | 280 | Winneshiek | 43 15 45 N | 091 39 56 W |
| Trout River Post Office (historical) | Post Office | 357 | Winneshiek | 43 13 40 N | 091 40 31 W |
| Trout Run | Stream | | Allamakee | 43 18 12 N | 091 18 32 W |
| Trout Run | Stream | | Winneshiek | 43 17 27 N | 091 45 31 W |
| Trout Run Access Area | Locale | 262 | Winneshiek | 43 17 10 N | 091 45 56 W |
| Trowbridge Cemetery | Cemetery | 207 | Johnson | 41 33 05 N | 091 27 31 W |
| Trowbridge Hall | Building | 205 | Johnson | 41 39 47 N | 091 32 13 W |
| Trowbridge Marsh | Park | 302 | Floyd | 43 04 30 N | 092 41 46 W |
| Troy | Populated Place | 244 | Davis | 40 44 55 N | 092 12 10 W |
| Troy (historical) | Locale | 264 | Lucas | 41 02 12 N | 093 25 33 W |
| Troy (historical) | Populated Place | 264 | Lucas | 41 02 12 N | 093 25 33 W |
| Troy Academy (historical) | School | 244 | Davis | 40 44 55 N | 092 12 10 W |
| Troy Cemetery | Cemetery | 352 | Clarke | 41 01 10 N | 093 59 01 W |
| Troy Cemetery | Cemetery | 247 | Davis | 40 45 10 N | 092 12 22 W |
| Troy Cemetery | Cemetery | 328 | Wright | 42 36 04 N | 093 54 29 W |
| Troy Creek | Stream | | Jefferson | 40 54 52 N | 091 53 48 W |
| Troy Elevator | Locale | 244 | Davis | 40 44 55 N | 092 12 10 W |
| Troy Mills | Populated Place | 265 | Linn | 42 17 24 N | 091 40 57 W |
| Troy Mills Cemetery | Cemetery | 271 | Linn | 42 17 01 N | 091 41 47 W |
| Troy Mills Post Office | Post Office | 265 | Linn | 42 17 24 N | 091 40 57 W |
| Troy Mills State Fish and Game Area | Park | 260 | Buchanan | 42 18 54 N | 091 43 21 W |
| Troy Mills Wapsie County Park | Park | 263 | Buchanan | 42 19 13 N | 091 43 22 W |
| Troy Park | Park | 244 | Davis | 40 44 55 N | 092 12 11 W |
| Troy Park | Park | 330 | Wright | 42 36 03 N | 093 54 41 W |
| Troy Post Office (historical) | Post Office | 244 | Davis | 40 44 55 N | 092 12 10 W |
| Troy Safety Rest Area | Locale | 337 | Wright | 42 35 57 N | 093 54 45 W |
| Truax Post Office (historical) | Post Office | 224 | Mahaska | 41 11 36 N | 092 43 51 W |
| True Bible Baptist Church | Church | 256 | Polk | 41 38 07 N | 093 36 40 W |
| True Life Assembly | Church | 252 | Polk | 41 37 32 N | 093 32 47 W |
| Trueblood Cemetery | Cemetery | 201 | Keokuk | 41 15 30 N | 092 09 01 W |
| Truesdale | Populated Place | 417 | Buena Vista | 42 43 45 N | 095 10 58 W |
| Truesdale (historical) | Locale | 417 | Buena Vista | 42 43 45 N | 095 10 58 W |
| Truesdale Post Office | Post Office | 417 | Buena Vista | 42 43 45 N | 095 10 58 W |
| Truhlar Cemetery | Cemetery | 248 | Linn | 41 51 44 N | 091 37 03 W |
| Trullinger Cemetery | Cemetery | 318 | Decatur | 40 46 58 N | 093 38 00 W |
| Trulner Creek | Stream | | Humboldt | 42 51 49 N | 094 12 33 W |
| Truman School | School | 260 | Linn | 41 58 38 N | 091 44 23 W |
| Trumbo Cemetery | Cemetery | 226 | Van Buren | 40 49 00 N | 091 50 31 W |
| Trumbull Lake | Lake | 409 | Clay | 43 11 31 N | 094 56 56 W |
| Trumbull Lake State Game Management Area | Park | 409 | Clay | 43 11 35 N | 094 56 55 W |
| Truro | Populated Place | 330 | Madison | 41 12 35 N | 093 50 48 W |
| Truro (historical) | Locale | 330 | Madison | 41 12 35 N | 093 50 48 W |
| Truro City Hall | Building | 330 | Madison | 41 12 28 N | 093 50 51 W |
| Truro Fire Department | Building | 330 | Madison | 41 12 35 N | 093 50 48 W |
| Truro Post Office | Post Office | 329 | Madison | 41 12 34 N | 093 50 42 W |
| Truro Public Library | Building | 328 | Madison | 41 12 28 N | 093 50 47 W |
| Trussell Cemetery | Cemetery | 283 | Monroe | 40 55 14 N | 092 40 08 W |
| Trustee Hall | Building | 247 | Wapello | 41 02 45 N | 092 23 41 W |
| Truth Seekers Bible Temple | Church | 273 | Polk | 41 36 02 N | 093 37 32 W |
| Tubaugh Family Chiropractic Clinic | Hospital | 296 | Appanoose | 40 43 55 N | 092 52 03 W |
| Tubaugh Wildlife Area | Park | 287 | Appanoose | 40 52 00 N | 092 43 51 W |
| Tucker Cemetery | Cemetery | 347 | Mitchell | 43 14 58 N | 092 49 56 W |
| Tucker Creek | Stream | | Crawford | 42 09 25 N | 095 14 55 W |
| Tucker Park | Park | 416 | Crawford | 42 01 42 N | 095 20 31 W |
| Tucker Park | Park | 248 | Linn | 42 02 16 N | 091 40 02 W |
| Tuckers Creek | Stream | | Ringgold | 40 37 24 N | 094 08 31 W |
| Tuecke Hollow | Valley | | Clayton | 42 46 12 N | 091 13 33 W |
| Tug Fork Big Indian Creek | Stream | | Van Buren | 40 39 35 N | 091 56 53 W |
| Tug Fork Big Indian Creek | Stream | | Van Buren | 40 41 45 N | 092 01 13 W |
| Tulip Toren | Locale | 251 | Marion | 41 24 50 N | 092 54 35 W |
| Tumelty Park | Park | 187 | Lee | 40 24 29 N | 091 23 23 W |
| Tunis Post Office (historical) | Post Office | 237 | Wapello | 41 01 02 N | 092 17 46 W |
| Tunnel (historical) | Locale | 330 | Hamilton | 42 21 13 N | 093 50 51 W |
| Tunnel Mill Area | Park | 317 | Hamilton | 42 20 50 N | 093 51 41 W |