The riding of Stormont-Dundas-South Glengarry lies on the north shore of the St. Lawrence River up to the Quebec border. It contains the townships of South Glengarry, North Stormont, South Stormont, North Dundas and South Dundas.
The city of Cornwall accounts for about half of the riding’s population. The rest of the riding is largely rural and includes Winchester, Chesterville, Iroquois, Finch, Morrisburg and the part of the Akwesasne Indian Reserve that is in Ontario.