Resident Population in Riley County, KS was 71.40200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Riley County, KS reached a record high of 77.54500 in January of 2012 and a record low of 56.78800 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Riley County, KS - last updated from the United States Federal Reserve on May of 2024.