Cimarron County is the westernmost county in the U.S. state of Oklahoma. Its county seat is Boise City. As of the 2020 census, its population was 2,296, making it the least-populous county in Oklahoma; and indeed, throughout most of its history, it has had both the smallest population and the lowest population density of any county in Oklahoma. Located in the Oklahoma Panhandle, Cimarron County contains the only community in the state that observes the Mountain Time Zone.