The Intermountain Region of North America is framed on the east by the Rocky Mountains of Canada and the United States and on the west by the Cascade and the Sierra Nevada ranges. Ethnographers customarily divide this region into two indigenous "culture areas," the Plateau and the Great Basin. The Plateau is bounded on the north by the boreal forests beyond the Fraser Plateau of British Columbia and on the south by the Bitterroot Mountains of Idaho and the arid highlands of southern Oregon and northwestern Montana. It includes the Columbia River's plateau and drainage in Washington, Oregon, and a small portion of northern California. The Great Basin is the area of steppe-desert lying primarily in Nevada and Utah but including parts of southern Idaho, western Wyoming, and western Colorado. It runs south from the Salmon...