5 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Trumbull | Greater Bridgeport Planning Region | 38,544 |
| Torrington | Northwest Hills Planning Region | 35,750 |
| Tolland | Capitol Planning Region | 14,823 |
| Thompson | Northeastern CT Planning Region | 9,628 |
| Thomaston | Naugatuck Valley Planning Region | 7,600 |