Catron County is a county in the U.S. state of New Mexico. As of the 2020 census, the population was 3,579, making it New Mexico's third-least populous county. Its county seat is Reserve. Catron County is New Mexico's largest county by area.

Socorro County is a county in the U.S. state of New Mexico. As of the 2020 census, the population was 16,595. The county seat is Socorro. The county was formed in 1852 as one of the original nine counties of New Mexico Territory. Socorro was originally the name given to a Native American village by Don Juan de Oñate in 1598. Having received vitally needed food and assistance from the native population, Oñate named the pueblo Socorro.