Plainfield is a town on the northwestern edge of Hampshire County, Massachusetts, United States, about 25 miles east of Pittsfield and 30 miles northwest of Northampton. The population was 648 at the 2010 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area.
Plainfield was first settled in 1770, primarily by settlers from the town of Bridgewater, and was officially incorporated as a district within the Town of Cummington in 1785, and as a town on June 15, 1807. Plainfield is currently the youngest town in Hampshire County, a distinction it has held since the disincorporation of Enfield (1816) and Prescott (1822) in 1938.
In the 1800s, Plainfield was a thriving agricultural community, primarily producing sheep and leather for tanning. With the widespread adoption of the steamship, and the resultant globalization in the 1870s, the expense of importing both mutton and leather from Australia and New Zealand was greatly reduced. Consequently, the agricultural industries in Plainfield became less profitable, and the Population declined substantially over the following decades.
Sixty-one men from Plainfield joined the Union Army late in the American Civil War. Six were killed in battle, or died in consequence of their service. Of those who survived, many settled elsewhere after the war.
After almost two centuries of depopulation, modern Plainfield is experiencing increased population growth (as of 2010).