Resident Population in Marion County, FL was 409.95900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Marion County, FL reached a record high of 409.95900 in January of 2023 and a record low of 69.03000 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Marion County, FL - last updated from the United States Federal Reserve on May of 2024.