South Lake Tahoe is the most populous city in El Dorado County, California, in the Sierra Nevada Mountains. The population was 21,403 at the 2010 census, down from 23,609 at the 2000 census. The east end of the city, on the California-Nevada state line, 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, Nevada. The city extends about five miles (8 km) west-southwest along U.S. Route 50, also known as Lake Tahoe Blvd. The western end of town is mainly residential, and clusters around "The Y" (new intersection October 2008), the X-shaped intersection of US 50, State Route 89, and the continuation of Lake Tahoe Boulevard after it loses its Federal highway designation.