Harriman State Park in eastern Idaho occupies eleven thousand acres within the Henry's Fork Caldera and the Greater Yellowstone Ecosystem, about three miles south of Island Park. Long owned by Union Pacific Railroad investors as a cattle ranch and private retreat for the Harriman and Guggenheim families, the property was deeded to Idaho at no cost by Roland and W. Averell Harriman in 1977 and opened to the public in 1982. Known for both scenery and wildlife, it supports elk, moose, sandhill cranes, trumpeter swans, and occasionally bears. Henrys Fork runs eight miles through its meadows, and the park is especially important as winter habitat for two-thirds of the contiguous United States' trumpeter swans.