[3] The land where Cromwell is now located, was once named for the Mattabesset, a region and settlement that was once home to Eastern Algonquian language-speaking Native Americans.

As Middletown began to emerge as one of the busiest ports in New England, the Upper Houses also boasted its own expansion of maritime industries.

In the 19th century, the War of 1812 limited maritime trade creating a decline in the Upper Houses.

Some continued to pursue maritime industry, the village generally reverted back to its agricultural beginnings.

Pierson’s Inc.[8] The company started as a small floral nursery, and later evolved into the largest commercial rose growing enterprise in the country.

Irish, German and Italian immigrants found housing along the river on lower Main Street, in areas that were more prone to flooding.

[5] With the expansion of the Upper Houses, and the geographical barriers around the town it became increasingly difficult to maintain connection with the larger city of Middletown.

Initially, the Upper Houses was able to meet the needs of its residents with the creation of its own school and church, but by the mid-19th century, a stronger movement to become independent of Middletown had developed.

In 1851, the General Assembly of the State of Connecticut recognized Cromwell as a new town with a population of 1,259.

Post-World War II the town began to change significantly, including growth in population.

The Central Connecticut Expressway (Route 9), opened at the end of 1989, enhances the Town's location as it connects to I-95 in Old Saybrook, I-91 in Cromwell and I-84, the state's major east–west highway in New Britain.

The Fire Department also operates ambulances to provided Emergency Medical Care to residents and visitors.

Top employers in Cromwell according to the town's 2023 Comprehensive Annual Financial Report[28]