Williamsport is a city in and the county seat of Lycoming County, Pennsylvania, United States. As of the 2020 census, it had a population of 27,754. It is the principal city of the Williamsport Metropolitan Statistical Area, which has a population of about 114,000. Williamsport is the larger principal city of the Williamsport-Lock Haven Combined Statistical Area, which includes Lycoming and Clinton counties.