Salt Lake County is located in the U.S. state of Utah. As of the 2020 United States census, the population was 1,185,238, making it the most populous county in Utah. Its county seat and largest city is Salt Lake City, the state capital. The county was created in 1850. Salt Lake County is the 37th most populated county in the United States and is one of four counties in the Rocky Mountains to make it into the top 100. Salt Lake County has been the only county of the first class in Utah – under the Utah Code is a county with a population of 700,000 or greater. Although, Utah County directly to the south has recently reached this threshold.

Utah is a landlocked state in the Mountain West subregion of the Western United States. It borders Colorado to its east, Wyoming to its northeast, Idaho to its north, Arizona to its south, and Nevada to its west. Utah also touches a corner of New Mexico in the southeast. Of the fifty U.S. states, Utah is the 13th-largest by area; with a population over three million, it is the 30th-most-populous and 11th-least-densely populated. Urban development is mostly concentrated in two areas: the Wasatch Front in the north-central part of the state, which is home to roughly two-thirds of the population and includes the capital city, Salt Lake City; and Washington County in the southwest, with more than 180,000 residents. Most of the western half of Utah lies in the Great Basin.