Identifiers: city · CDP · borough
| Rank | Community | Population |
|---|---|---|
| 1 | Norwich (city), CT | 40,125 |
| 2 | New London (city), CT | 27,367 |
| 3 | Groton (city), CT | 9,387 |
| 4 | Conning Towers-Nautilus Park (CDP), CT | 8,870 |
| 5 | Pawcatuck (CDP), CT | 5,433 |
| 6 | Mystic (CDP), CT | 4,348 |
| 7 | Long Hill (CDP), CT | 3,948 |
| 8 | Old Mystic (CDP), CT | 3,493 |
| 9 | Niantic (CDP), CT | 3,194 |
| 10 | Waterford (CDP), CT | 3,074 |
| 11 | Oxoboxo River (CDP), CT | 2,955 |
| 12 | Noank (CDP), CT | 1,654 |
| 13 | Gales Ferry (CDP), CT | 1,159 |
| 14 | Stonington (borough), CT | 976 |
| 15 | Groton Long Point (borough), CT | 530 |