Suffield is a town in Hartford County, Connecticut, United States. It had once been within the boundaries of Massachusetts. The town is located in the Connecticut River Valley with the town of Enfield neighboring to the east. In 1900, 3,521 people lived in Suffield; as of the 2010 census, the population was 15,735. The town center is a census-designated place listed as Suffield Depot in U.S. Census records.