Resident Population in Jefferson County, WI was 85.74300 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Jefferson County, WI reached a record high of 86.19300 in January of 2020 and a record low of 60.06000 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Jefferson County, WI - last updated from the United States Federal Reserve on May of 2024.