Farmington Township is a township in Clarion County, Pennsylvania, United States. The population was 1,779 at the 2020 census, a decrease from 1,934 at the 2010 census. The township is located in the northeastern corner of Clarion County and is bordered by Forest County to the north and east. A small part of the eastern border of the township touches …Farmington Township is a township in Clarion County, Pennsylvania, United States. The population was 1,779 at the 2020 census, a decrease from 1,934 at the 2010 census. The township is located in the northeastern corner of Clarion County and is bordered by Forest County to the north and east. A small part of the eastern border of the township touches Jefferson County. The Clarion River forms the southeastern border of the township.