Resident Population in Arapahoe County, CO was 656.06100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Arapahoe County, CO reached a record high of 656.55700 in January of 2021 and a record low of 162.14200 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Arapahoe County, CO - last updated from the United States Federal Reserve on May of 2024.