of subalpine forests. Yellowstone's bison herds make up the largest bison population in the United States and are notable for being one of the few bison herds that has not been altered by inbreeding with cattle. Further reading See also List of Idaho state parks History of the National Park Service List of areas in the United States National Park System List of national parks of the United States National Park Service Notes References External links National Park Service National Parks in Idaho, Everything Everywhere. NPS: Geology of Craters of the Moon. National Park Service areas in Idaho Natural history of Idaho