Elko County is a county located in the U.S. state of Nevada. As of the 2010 census, the population was 48,818. Its county seat is Elko. The county was established on March 5, 1869, from Lander County. The county shares a border with the state of Idaho to the north, the state of Utah to the east, White Pine County to the south, Eureka County and Lander County to the southwest, and Humboldt County to the west.
Elko County is the fourth-largest county in the contiguous United States, ranking lower when the boroughs of Alaska are included. It is also one of only 10 counties in the U.S. with more than 10,000 square miles of area.
Elko County is part of the Elko, NV Micropolitan Statistical Area.