Dartmouth is a coastal town in Bristol County, Massachusetts, United States. Old Dartmouth was the first area of Southeastern Massachus…Dartmouth is a coastal town in Bristol County, Massachusetts, United States. Old Dartmouth was the first area of Southeastern Massachusetts to be settled by Europeans in 1652, primarily English. Dartmouth is part of New England's farm coast, which consists of a chain of historic coastal villages, vineyards, and farms. June 8, 2014, marked the 350th year of Dartmouth's incorporation as a town. It is also part of the Massachusetts South Coast.