Resident Population in Marion County, OH was 64.85100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Marion County, OH reached a record high of 67.97400 in January of 1980 and a record low of 64.06600 in January of 1988. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Marion County, OH - last updated from the United States Federal Reserve on May of 2024.