Identifiers: city · CDP · borough
| Rank | Community | Population |
|---|---|---|
| 1 | Norwich (city), CT | 40,125 |
| 2 | New London (city), CT | 27,367 |
| 3 | Willimantic (CDP), CT | 18,149 |
| 4 | Putnam (CDP), CT | 7,065 |
| 5 | Colchester (CDP), CT | 4,700 |
| 6 | Danielson (borough), CT | 4,155 |
| 7 | Jewett City (borough), CT | 3,328 |
| 8 | Moosup (CDP), CT | 3,113 |
| 9 | Waterford (CDP), CT | 3,074 |
| 10 | Oxoboxo River (CDP), CT | 2,955 |
| 11 | Plainfield Village (CDP), CT | 2,580 |
| 12 | East Brooklyn (CDP), CT | 2,205 |
| 13 | Wauregan (CDP), CT | 1,539 |
| 14 | Baltic (CDP), CT | 1,186 |
| 15 | Gales Ferry (CDP), CT | 1,159 |
| 16 | Brooklyn (CDP), CT | 952 |
| 17 | Dayville (CDP), CT | 631 |
| 18 | Mashantucket (CDP), CT | 457 |