The Cordilleran ice sheet was a major ice sheet that periodically covered large parts of North America during glacial periods over the last ~2.6 million years. This included the following areas: * Western Montana * The Idaho Panhandle * Northern Washington state down to about Olympia and Spokane * All of British Columbia * The southwestern third or so of Yukon Territory * All of the Alaska Panhandle * South Central Alaska * The Alaska Peninsula * Almost all of the continental shelf north of the Strait of Juan de Fuca