South Lake Tahoe is the most populous city in El Dorado County, California, United States, in the Sierra Nevada. As its name suggests, the city is located on the southern shore of Lake Tahoe.The city's population was 21,403 at the 2010 census, down from 23,609 at the 2000 census. The city extends about 5 miles 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, with T-shirt shops, 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 X-shaped intersection of US 50, State Route 89, and the continuation of Lake Tahoe Boulevard after it loses its federal highway designation.