Resident Population in San Luis Obispo County, CA was 281.63900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in San Luis Obispo County, CA reached a record high of 283.25000 in January of 2018 and a record low of 105.69000 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in San Luis Obispo County, CA - last updated from the United States Federal Reserve on May of 2024.