Costilla County is a county in the State of Colorado of the United States. The county population was 3,721 at U.S. Census 2016. The county seat is San Luis.
History
Costilla County was the first area of Colorado to be settled by European-Americans. Hispanic settlers from Taos, New Mexico, officially established San Luis on 1851-04-09. Costilla County was one of the original 17 counties created by the Territory of Colorado on 1861-11-01. The county was named for the Costilla River. Although San Miguel was originally designated the county seat, the county government was moved to San Luis in 1863.
