Fishers are widespread throughout the northern forests of North America. They are found in the boreal and mixed deciduous-coniferous forest belt that runs across Canada from Nova Scotia in the east to the Pacific shore of British Columbia and north to Alaska. They can be found as far north as Great Slave Lake in the Northwest Territories and as far south as the mountains of Oregon. Isolated populations occur in the Sierra Nevada of California, throughout New England and the Appalachian Mountains of Pennsylvania, Maryland, West Virginia, and Virginia.