According to the U.S. Census Bureau, the county has a total area of 17,203 square miles (44,560 km²), of which 17,170 square miles (44,500 km²) is land and 33 square miles (85 km²) (0.2%) 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 (behind 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 11,387 feet (3,471 m) on the summit of Ruby Dome in the Ruby Mountains.
The most topographically prominent mountain in Elko County is Pilot Peak.

The county has three physiographic sections (70% Great Basin section, 20% Payette, 10% Snake River Plain) and 4 watersheds (45% Humboldt River, 30% Upper Snake River, 20% central Nevada desert, 5% Pilot-Thousand Springs).
According to the U.S. Census Bureau, the county has a total area of 17,203 square miles (44,560 km²), of which 17,170 square miles (44,500 km²) is land and 33 square miles (85 km²) (0.2%) 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 (behind 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 11,387 feet (3,471 m) on the summit of Ruby Dome in the Ruby Mountains. The most topographically prominent mountain in Elko County is Pilot Peak.
The county has three physiographic sections (70% Great Basin section, 20% Payette, 10% Snake River Plain) and 4 watersheds (45% Humboldt River, 30% Upper Snake River, 20% central Nevada desert, 5% Pilot-Thousand Springs).
Elko County, Nevada