Resident Population in Costilla County, CO was 3.62800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Costilla County, CO reached a record high of 3.87200 in January of 2019 and a record low of 3.04500 in January of 1981. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Costilla County, CO - last updated from the United States Federal Reserve on May of 2024.