La Plata County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 55,638. The county seat is Durango. The county was named for the La Plata River and the La Plata Mountains. "La plata" means "the silver" in Spanish. La Plata County comprises the Durango, CO Micropolitan Statistical Area. The county is home to Durango Rock Shelters Archeology Site, the type site for the Basketmaker II period of Anasazi culture.