South Lake Tahoe is the most populous city in El Dorado County, California, United States, in the Sierra Nevada mountains. The city's population was 21,330 at the 2020 census, down from 21,403 at the 2010 census. The city, along the southern edge of Lake Tahoe, extends about 5 miles (8 km) west-southwest along U.S. Route 50, also known as Lake Tahoe Boulevard. The east end of the city, on the California–Nevada state line right next to the town of Stateline, Nevada, is mainly geared towards tourism, restaurants, hotels, and Heavenly Mountain Resort with the Nevada casinos just across the state line in Stateline. The western end of town is mainly residential, and clusters around "The Y", the intersection of US 50, State Route 89, and the continuation of Lake Tahoe Boulevard after it loses its federal highway designation.

El Dorado County, officially the County of El Dorado, is a county located in the U.S. state of California. As of the 2020 census, the population was 191,185. The county seat is Placerville. The county is part of the Sacramento-Roseville-Arden-Arcade, CA Metropolitan Statistical Area. It is located entirely in the Sierra Nevada, from the historic Gold Country in the western foothills to the High Sierra in the east. El Dorado County's population has grown as Greater Sacramento has expanded into the region. Where the county line crosses US 50 at Clarksville, the distance to Sacramento is 15 miles. In the county's high altitude eastern end at Lake Tahoe, environmental awareness and environmental protection initiatives have grown along with the population since the 1960 Winter Olympics, hosted at the former Squaw Valley Ski Resort in neighboring Placer County.