Northern white-cedar is native to an area in the southern part of eastern Canada and the adjacent part of the northern United States. It extends from southeastern Manitoba east throughout the Great Lakes region and into Ontario, Québec, New York, Vermont, New Hampshire, Maine, Prince Edward Island, New Brunswick, and Nova Scotia. There are isolated populations in west-central Manitoba, and to the south in Massachusetts, Connecticut, Ohio, and Illinois and in the Appalachian Mountains of Kentucky, Tennessee, North Carolina, Pennsylvania, Maryland, Virginia, and West Virginia. In Canada, its range reaches the Arctic treeline and the southern tip of Hudson Bay. It grows mainly in places with cooler summers, with an average temperature of in July, and a shorter growing season, from 90 to 180 days.