Resident Population in Marion County, IN was 968.46000 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Marion County, IN reached a record high of 976.63100 in January of 2020 and a record low of 765.23300 in January of 1980. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Marion County, IN - last updated from the United States Federal Reserve on May of 2024.