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.