Antelope Islan, with an area of 42 square miles (68 km²), is the largest island in the Great Salt Lake, the largest lake in the Western United States, and the largest saltwater lake in the Western Hemisphere. The island lies entirely within Davis County, in the southeastern portion of the lake and becomes a peninsula when the lake is at extremely low levels. Antelope Island holds populations of pronghorn antelope, bighorn sheep, 600 American Bison and millions of waterfowl. The Bison were introduced to the island in 1893, and have proven to be a valuable genetic pool for Bison breeding and conservation purposes.