Resident Population in Lyon County, IA was 12.37800 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Lyon County, IA reached a record high of 13.40000 in January of 1973 and a record low of 11.19500 in January of 2009. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Lyon County, IA - last updated from the United States Federal Reserve on April of 2026.