Coordinates: 41.13°N 115.35°W / 41.13°N 115.35°W / 41.13; -115.35

Elko County is a county located in the U.S. state of Nevada. As of the 2010 census, the population was 48,818. As of July 1, 2007, the population of Elko County was estimated at 50,434. Its county seat is Elko. The county was established on March 5, 1869, from Lander County. Elko County is the fourth-largest county in the contiguous United States, ranking lower when the boroughs of Alaska are included.

Elko County is part of the Elko micropolitan area.

Elko County was established in 1869 from Lander County and the name was taken from the Shoshoni word for "white woman".

According to the U.S. Census Bureau, the county has a total area of 17,203 square miles (44,555.6 km²), of which 17,179 square miles (44,493.4 km²) is land and 24 square miles (62.2 km²) (0.14%) is water. Not counting Alaska's boroughs (four of which are also larger), it is the fourth largest county in area in the United States (cf. San Bernardino County, California, Coconino County, Arizona, and Nye County, Nevada). The elevation ranges from about 4,300 feet (1,300 m) at the edge of the salt flats of the Great Salt Lake Desert, to 11,157 feet (3,401 m) in the Ruby Mountains.

Nevada (ⁱ/nəˈvædə/ or /nəˈvɒdə/) is a state in the western, mountain west, and southwestern regions of the United States. Nevada is the 7th most extensive, the 35th most populous, and the 9th least densely populated of the 50 United States. Over two-thirds of Nevada's people live in one single county, Clark County, which contains the Las Vegas–Paradise metropolitan area, where the state's three largest incorporated cities are located. Nevada's capital is Carson City.

Nevada is largely desert and semiarid, with much of it located within the Great Basin. Areas south of the Great Basin are located within the Mojave Desert, while Lake Tahoe and the Sierra Nevada mountains lie on the western edge. Approximately 86% of the state's land is owned by the US government under various jurisdictions, both civilian and military.

The name Nevada is derived from the nearby Sierra Nevada mountains, which means "snow-capped mountain range" in Spanish. The land comprising the modern state was inhabited by Native Americans of the Paiute, Shoshone, and Washoe tribes prior to European contact. It was subsequently claimed by Spain as a part of Alta California until the Mexican War of Independence brought it under Mexican control. The United States gained the territory in 1848 following its victory in the Mexican-American War and the area was eventually incorporated as part of Utah Territory in 1850. The discovery of silver at the Comstock Lode in 1859 led to a population boom that was an impetus to the creation of Nevada Territory out of western Utah Territory in 1861. Nevada became the 36th state on October 31, 1864.