Resident Population in Jefferson County, KY was 772.14400 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Jefferson County, KY reached a record high of 782.78300 in January of 2020 and a record low of 666.02900 in January of 1989. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Jefferson County, KY - last updated from the United States Federal Reserve on May of 2024.