Resident Population in Simpson County, MS was 25.59700 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Simpson County, MS reached a record high of 28.05400 in January of 2008 and a record low of 19.90000 in January of 1971. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Simpson County, MS - last updated from the United States Federal Reserve on April of 2026.