Resident Population in Boulder County, CO was 326.83100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Boulder County, CO reached a record high of 330.92200 in January of 2020 and a record low of 131.88900 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Boulder County, CO - last updated from the United States Federal Reserve on May of 2024.