Resident Population in Johnson County, MO was 54.96200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Johnson County, MO reached a record high of 54.96200 in January of 2023 and a record low of 33.80000 in January of 1975. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Johnson County, MO - last updated from the United States Federal Reserve on May of 2024.