Resident Population in Sullivan County, PA was 5.83400 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Sullivan County, PA reached a record high of 6.57700 in January of 2001 and a record low of 5.82300 in January of 2020. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Sullivan County, PA - last updated from the United States Federal Reserve on May of 2024.