Resident Population in Clay County, MS was 18.21300 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Clay County, MS reached a record high of 21.98500 in January of 2000 and a record low of 18.21300 in January of 2024. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Clay County, MS - last updated from the United States Federal Reserve on April of 2026.