Resident Population in Mills County, IA was 14.63300 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Mills County, IA reached a record high of 15.18100 in January of 2007 and a record low of 11.83200 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Mills County, IA - last updated from the United States Federal Reserve on May of 2024.