Resident Population in Waukesha County, WI was 412.59100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Waukesha County, WI reached a record high of 412.59100 in January of 2023 and a record low of 231.33500 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Waukesha County, WI - last updated from the United States Federal Reserve on May of 2024.