Elko County is a county in the northeastern corner of Nevada, United States. As of the 2020 census, the population was 53,702. Its county seat is Elko. The county was established on March 5, 1869, from Lander County. Elko County is the fourth-largest county by area in the contiguous United States, ranking lower when the boroughs of Alaska are included. It is one of only 10 counties in the U.S. with more than 10,000 square miles of area.