Greenville is a town on the northern border of Greene County, New York, United States. The population was 3,741 at the 2020 census. The town contains a hamlet also named Greenville. The area of the town was first settled circa 1774. The town was established in 1803 as "Greenfield" from the towns of Coxsackie and Durham. The adjoining town is "Freehold…Greenville is a town on the northern border of Greene County, New York, United States. The population was 3,741 at the 2020 census. The town contains a hamlet also named Greenville. The area of the town was first settled circa 1774. The town was established in 1803 as "Greenfield" from the towns of Coxsackie and Durham. The adjoining town is "Freehold", just south of Greenville.