Fairfield Township is a township in Lycoming County, Pennsylvania, United States. The population was 2,833 at the 2020 census. It is part of the Williamsport Metropolitan Statistical Area. The exact date of the formation of Fairfield Township is not known, but court records point to sometime between August 1825 and December 1826. A petition for t…Fairfield Township is a township in Lycoming County, Pennsylvania, United States. The population was 2,833 at the 2020 census. It is part of the Williamsport Metropolitan Statistical Area. The exact date of the formation of Fairfield Township is not known, but court records point to sometime between August 1825 and December 1826. A petition for the division of Muncy Township was read in court in August 1825. Historical records do not record when the township was formed, but court documents cite Fairfield Township as the residence of a defendant in a lawsuit in a Columbia County court session in 1826.