Resident Population in Gregory County, SD was 4.01800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Gregory County, SD reached a record high of 6.80000 in January of 1971 and a record low of 3.95200 in January of 2021. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Gregory County, SD - last updated from the United States Federal Reserve on May of 2024.