Founded in 1785, Middlesex County is one of 8 counties in the state of Connecticut. Historically, Middlesex County was formed from parts of Hartford and New London Counties. The city of Middletown is the county seat. With FIPS code of 7, Middlesex County has a population of 164,759 and area of 369 square miles (956 km2).
List of all cities in Middlesex County, CT alphabetically
| City/Town | Postal Code | Area Code |
| Centerbrook, CT | 06409 | 860/959 |
| Chester, CT | 06412 | 860/959 |
| Clinton, CT | 06413 | 860/959 |
| Cobalt, CT | 06414 | 860/959 |
| Cromwell, CT | 06416 | 860/959 |
| Deep River, CT | 06417 | 860/959 |
| 06419 | 860/959 | |
| Durham, CT | 06422 | 860/959 |
| East Haddam, CT | 06423 | 860/959 |
| 06424 | 860/959 | |
| Essex, CT | 06426 | 860/959 |
| Fenwick, CT | 06475 | 860/959 |
| Haddam, CT | 06438 | 860/959 |
| Haddam Neck, CT | 06424 | 860/959 |
| Higganum, CT | 06441 | 860/959 |
| Ivoryton, CT | 06442 | 860/959 |
| Killingworth, CT | 06419 | 860/959 |
| Middle Haddam, CT | 06456 | 860/959 |
| Middlefield, CT | 06455 | 860/959 |
| Middletown, CT | 06457 | 860/959 |
| 06459 | 860/959 | |
| Moodus, CT | 06469 | 860/959 |
| Old Saybrook, CT | 06475 | 860/959 |
| Portland, CT | 06480 | 860/959 |
| Rockfall, CT | 06481 | 860/959 |
| Wesleyan, CT | 06459 | 860/959 |
| Westbrook, CT | 06498 | 860/959 |
Map of Cities in Middlesex County, CT
