5 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Trumbull | Greater Bridgeport Planning Region | 37,707 |
| Torrington | Northwest Hills Planning Region | 35,673 |
| Tolland | Capitol Planning Region | 14,642 |
| Thompson | Northeastern CT Planning Region | 9,529 |
| Thomaston | Naugatuck Valley Planning Region | 7,565 |