Washington County is a county in the southwestern corner of Utah, United States. As of the 2020 United States Census, the population was 180,279, making it the fifth-most populous county in Utah. Its county seat and largest city is St. George. The county was created in 1852 and organized in 1856. It was named after the first President of the United States, George Washington. A portion of the Paiute Indian Reservation is in western Washington County. Washington County comprises the St. George, UT Metropolitan Statistical Area.

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.