Resident Population in Grundy County, MO was 9.76600 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Grundy County, MO reached a record high of 12.20000 in January of 1979 and a record low of 9.75700 in January of 2020. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Grundy County, MO - last updated from the United States Federal Reserve on April of 2026.