Resident Population in Marion County, SC was 28.50800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Marion County, SC reached a record high of 35.65800 in January of 1997 and a record low of 28.45000 in January of 2022. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Marion County, SC - last updated from the United States Federal Reserve on May of 2024.