Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Tunnel Post Office (historical) | Post Office | 296 | Hamilton | 42 21 00 N | 093 50 26 W |
| Turin | Populated Place | 321 | Monona | 42 01 10 N | 095 57 59 W |
| Turin (historical) | Locale | 321 | Monona | 42 01 10 N | 095 58 00 W |
| Turin Ciy Hall | Building | 321 | Monona | 42 01 10 N | 095 57 59 W |
| Turin Post Office | Post Office | 321 | Monona | 42 01 10 N | 095 57 59 W |
| Turkery Creek | Stream | | Warren | 41 15 35 N | 093 30 35 W |
| Turkey Bend Wildlife Area | Park | 366 | Howard | 43 20 45 N | 092 08 49 W |
| Turkey Creek | Stream | | Boone | 41 59 58 N | 093 54 22 W |
| Turkey Creek | Stream | | Cass | 41 19 25 N | 095 04 29 W |
| Turkey Creek | Stream | | Jasper | 41 45 11 N | 093 13 40 W |
| Turkey Creek | Stream | | Jefferson | 41 03 22 N | 091 44 04 W |
| Turkey Creek | Stream | | Johnson | 41 43 49 N | 091 31 17 W |
| Turkey Creek | Stream | | Polk | 41 49 42 N | 093 44 07 W |
| Turkey Creek | Stream | | Polk | 41 25 32 N | 093 22 19 W |
| Turkey Creek | Stream | | Ringgold | 40 44 22 N | 094 24 38 W |
| Turkey Creek | Stream | | Wapello | 40 57 31 N | 092 20 54 W |
| Turkey Creek | Stream | | Warren | 41 15 51 N | 093 40 04 W |
| Turkey Creek | Stream | | Wayne | 40 39 52 N | 093 30 10 W |
| Turkey Creek Education Area | Park | 378 | Cass | 41 18 30 N | 095 04 21 W |
| Turkey Island | Island | 165 | Louisa | 41 12 05 N | 091 04 42 W |
| Turkey Island | Island | 195 | Wapello | 41 01 42 N | 092 25 58 W |
| Turkey Ridge Wildlife Area | Park | 324 | Clarke | 40 57 15 N | 093 43 36 W |
| Turkey River | Populated Place | 204 | Clayton | 42 42 22 N | 091 01 33 W |
| Turkey River | Stream | | Clayton | 42 43 03 N | 091 00 43 W |
| Turkey River (historical) | Locale | 294 | Clayton | 42 40 50 N | 091 01 30 W |
| Turkey River Access State Wildlife Area | Area | 347 | Howard | 43 20 20 N | 092 05 58 W |
| Turkey River Area | Park | 356 | Winneshiek | 43 20 17 N | 092 05 49 W |
| Turkey River Bridge | Bridge | 292 | Winneshiek | 43 05 06 N | 091 53 38 W |
| Turkey River Mounds State Monument | Park | 238 | Clayton | 42 43 06 N | 091 02 46 W |
| Turkey River Mounds State Preserve | Park | 239 | Clayton | 42 43 05 N | 091 02 55 W |
| Turkey River Park | Park | 218 | Clayton | 42 50 35 N | 091 24 08 W |
| Turkey River Post Office (historical) | Post Office | 204 | Clayton | 42 42 22 N | 091 01 33 W |
| Turkey River Wildlife Area | Park | 362 | Howard | 43 21 60 N | 092 12 46 W |
| Turkey River Wildlife Area | Park | 366 | Howard | 43 20 10 N | 092 05 11 W |
| Turkey Run | Stream | | Decatur | 40 42 51 N | 093 38 25 W |
| Turkey Run | Stream | | Louisa | 41 13 06 N | 091 11 57 W |
| Turkey Run | Stream | | Mahaska | 41 11 55 N | 092 46 17 W |
| Turkey Run Access | Locale | 197 | Lee | 40 32 15 N | 091 36 51 W |
| Turkey Run Wildlife Area | Park | 229 | Jefferson | 40 54 30 N | 091 54 01 W |
| Turkey Towhead Island | Island | 165 | Louisa | 41 12 45 N | 091 05 23 W |
| Turkey Valley Community School | School | 354 | Winneshiek | 43 06 37 N | 092 02 07 W |
| Turkeyfoot Prairie | Area | 361 | Worth | 43 22 32 N | 093 10 49 W |
| Turner | Locale | 272 | Jasper | 41 42 08 N | 092 49 05 W |
| Turner (historical) | Populated Place | 272 | Jasper | 41 42 08 N | 092 49 05 W |
| Turner Cemetery | Cemetery | 260 | Black Hawk | 42 26 36 N | 092 17 36 W |
| Turner Cemetery | Cemetery | 312 | Tama | 42 02 08 N | 092 40 10 W |
| Turner Clinic | Hospital | 384 | Emmet | 43 23 56 N | 094 28 50 W |
| Turner Creek | Stream | | Fayette | 43 00 14 N | 091 53 26 W |
| Turner Creek | Stream | | Jasper | 41 39 60 N | 092 50 10 W |
| Turner Park | Park | 256 | Polk | 41 38 01 N | 093 36 31 W |
| Turner Plot Cemetery | Cemetery | 162 | Lee | 40 24 00 N | 091 26 51 W |
| Turner Post Office (historical) | Post Office | 272 | Jasper | 41 42 08 N | 092 49 05 W |
| Turner School (historical) | School | 209 | Clinton | 41 49 25 N | 090 28 14 W |
| Turtle Creek | Stream | | Delaware | 42 24 12 N | 091 22 45 W |
| Turtle Creek | Stream | | Mitchell | 43 22 45 N | 092 56 04 W |
| Turtle Creek Recreation Area | Park | 293 | Delaware | 42 24 16 N | 091 22 57 W |
| Turtle Island | Island | 158 | Des Moines | 40 52 08 N | 091 02 59 W |
| Turvoid Woods County Park | Park | 388 | Worth | 43 25 08 N | 093 18 43 W |
| Tusha Country School (historical) | School | 334 | Madison | 41 19 42 N | 094 00 51 W |
| Tuskeega (historical) | Locale | 357 | Decatur | 40 40 02 N | 093 59 02 W |
| Tuskeega Post Office (historical) | Post Office | 357 | Decatur | 40 40 02 N | 093 59 02 W |
| Tuskeego | Populated Place | 357 | Decatur | 40 39 60 N | 093 59 03 W |
| Tuttle Grove | Locale | 369 | Guthrie | 41 48 58 N | 094 43 11 W |
| Tuttle Grove Post Office (historical) | Post Office | 390 | Guthrie | 41 49 15 N | 094 43 11 W |
| Tuttle Lake County Park | Park | 379 | Emmet | 43 29 19 N | 094 37 01 W |
| Tuttle Lake State Game Management Area | Park | 374 | Emmet | 43 29 05 N | 094 34 35 W |
| Tuttle Marsh Area | Park | 415 | Clay | 43 13 00 N | 095 16 26 W |
| Tuttle Wildlife Area | Park | 243 | Benton | 41 53 20 N | 091 56 01 W |
| Tuttles Grove Cemetery | Cemetery | 397 | Guthrie | 41 48 47 N | 094 43 23 W |
| Twelve Mile Grove Post Office (historical) | Post Office | 356 | Harrison | 41 42 40 N | 095 41 01 W |
| Twelve Mile Lake | Reservoir | 348 | Union | 41 03 00 N | 094 15 04 W |
| Twelve Mile Lake Post Office (historical) | Post Office | 444 | Emmet | 43 17 30 N | 094 52 01 W |
| Twelve Mile Lake Wildlife Management Area | Park | 352 | Union | 41 04 20 N | 094 16 11 W |
| Twelvemile Creek | Stream | | Tama | 42 14 35 N | 092 24 12 W |
| Twelvemile Creek | Stream | | Union | 40 54 17 N | 094 01 34 W |
| Twelvemile Lake | Lake | 443 | Emmet | 43 17 22 N | 094 52 34 W |
| Twelvemile Lake State Game Management Area | Park | 443 | Emmet | 43 17 26 N | 094 52 30 W |
| Twenty-first Century Co-op Elevator | Locale | 387 | Cass | 41 16 20 N | 094 52 13 W |
| Twenty-Seven Flags Golf Course | Locale | 331 | Woodbury | 42 22 32 N | 096 22 29 W |
| Tweten Post Office (historical) | Post Office | 384 | Winnebago | 43 24 05 N | 093 39 16 W |
| Twilight Trailer Court | Populated Place | 433 | Sioux | 42 59 55 N | 096 04 03 W |
| Twin Acres Lake Dam | Dam | 305 | Scott | 42 00 25 N | 093 20 31 W |
| Twin Anchors Campground | Locale | 308 | Story | 42 00 27 N | 093 20 38 W |
| Twin Anchors Lake | Lake | 303 | Story | 42 00 19 N | 093 20 35 W |
| Twin Bridge | Bridge | 319 | Fayette | 42 49 05 N | 091 52 46 W |
| Twin Bridges County Park | Park | 322 | Fayette | 42 49 06 N | 091 52 48 W |
| Twin Bridges Park | Park | 285 | Delaware | 42 37 55 N | 091 16 50 W |
| Twin Cedars School | School | 225 | Marion | 41 13 05 N | 092 55 36 W |
| Twin Cities Church | Church | 296 | Pottawattamie | 41 13 03 N | 095 52 48 W |
| Twin City Park | Park | 296 | Pottawattamie | 41 13 29 N | 095 53 54 W |
| Twin Elms Access Area | Locale | 335 | Hardin | 42 26 57 N | 093 22 06 W |
| Twin Forks Wildlife Area | Park | 423 | Dickinson | 43 24 40 N | 095 15 09 W |
| Twin Grove Creek | Stream | | Keokuk | 41 12 10 N | 092 07 55 W |
| Twin Hills Beach | Beach | 429 | Dickinson | 43 23 02 N | 095 06 01 W |
| Twin Lake | Lake | 237 | Johnson | 41 49 00 N | 091 37 34 W |
| Twin Lakes | Lake | 180 | Jackson | 42 11 16 N | 090 19 23 W |
| Twin Lakes Bible Camp | Locale | 375 | Calhoun | 42 29 05 N | 094 38 14 W |
| Twin Lakes Cemetery | Cemetery | 374 | Calhoun | 42 26 34 N | 094 41 21 W |
| Twin Lakes Country Club | Locale | 217 | Henry | 41 07 50 N | 091 26 46 W |
| Twin Lakes Golf Club | Locale | 372 | Calhoun | 42 28 41 N | 094 38 31 W |
| Twin Lakes Post Office (historical) | Post Office | 369 | Calhoun | 42 28 50 N | 094 40 01 W |
| Twin Lakes State Park | Park | 374 | Calhoun | 42 29 34 N | 094 37 07 W |
| Twin Lakes State Park West | Park | 374 | Calhoun | 42 28 60 N | 094 38 39 W |
| Twin Lakes Trailer Court | Populated Place | 372 | Calhoun | 42 28 10 N | 094 38 39 W |
| Twin Oak | Locale | 191 | Washington | 41 21 45 N | 091 28 01 W |
| Twin Oak Post Office (historical) | Post Office | 197 | Louisa | 41 22 03 N | 091 27 58 W |
| Twin Oaks Campgrounds | Locale | 378 | Cerro Gordo | 43 06 35 N | 093 24 26 W |
| Twin Pine Mobile Home Park | Populated Place | 257 | Mahaska | 41 12 46 N | 092 25 31 W |
| Twin Pines Baptist Church | Church | 256 | Linn | 42 01 20 N | 091 40 41 W |
| Twin Pines Golf Course | Locale | 260 | Linn | 42 01 20 N | 091 41 43 W |