Amherst is a city in Hampshire County, Massachusetts, United States, in the Connecticut River valley. Amherst has a council–manager form of government, and is considered a city under Massachusetts state law. Amherst is one of several Massachusetts municipalities that have city forms of government but retain "The Town of" in their official names. At the 2020 census, the population was 39,263, making it the highest populated municipality in Hampshire County.