Resident Population in Mahaska County, IA was 21.87400 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Mahaska County, IA reached a record high of 23.00000 in January of 1978 and a record low of 21.41000 in January of 1989. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Mahaska County, IA - last updated from the United States Federal Reserve on May of 2024.