The title of Canada's largest steel producer is shared among key domestic manufacturing heavyweights that dominate the nation's industrial heartland, particularly in provinces like Ontario and Quebec. Companies such as Stelco and Algoma Steel have historically served as foundational pillars of Canadian heavy industry, producing millions of tons of hot-rolled, cold-rolled, and coated steel products for the automotive, construction, and energy sectors. These major domestic producers, alongside specialized regional mills and international subsidiaries operating within Canada's borders, collectively supply the vast majority of raw and finished steel products consumed across North American manufacturing supply chains.