Resident Population in Clayton County, IA was 16.96900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Clayton County, IA reached a record high of 21.80000 in January of 1977 and a record low of 16.96900 in January of 2023. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Clayton County, IA - last updated from the United States Federal Reserve on May of 2024.