St. George is a city in and the county seat of Washington County, Utah, United States. Located in the southwestern corner of the state on the Arizona border, it is the principal city of the St. George Metropolitan Statistical Area. The city lies in the northeasternmost part of the Mojave Desert, adjacent to the Pine Valley Mountains and near the convergence of three distinct geological areas: the Mojave Desert, Colorado Plateau, and Great Basin. The city is northeast of Las Vegas and south-southwest of Salt Lake City on Interstate 15.