The town, originally part of Plymouth, Connecticut, and referred to as 'Plymouth Hollow' was first settled in the early 1700s. It was incorporated in its own right and under the name 'Thomaston' in 1875. The name derives from Seth Thomas, the early clock maker, who established a factory in town. The Seth Thomas clock factory building still exists, however the clock making industry has long since left the state and eventually the country.
The Thomaston Dam Project has created a large watershed area visible from Route 222. The Thomaston Dam is across the Naugatuck River.
