Alamosa County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 16,376. The county seat is Alamosa. The county name is the Spanish language word for a grove
Costilla County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 3,499. The county seat is San Luis, the oldest continuously occupied town in Colorado.