Resident Population in Hamilton County, IA was 14.85600 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Hamilton County, IA reached a record high of 18.40000 in January of 1973 and a record low of 14.79700 in January of 2019. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Hamilton County, IA - last updated from the United States Federal Reserve on April of 2026.