In some parts of Canada—like Ontario, Quebec, and the Maritimes—milk comes in plastic bags instead of cartons or jugs. While unusual to outsiders, this packaging dates back to the late 1960s and has practical roots.

The Shift to Plastic Bags
Before 1967, Canadians used glass bottles for milk. When DuPont introduced lighter, cheaper plastic bags, they quickly caught on. Then, in 1970, Canada switched to the metric system. Rather than redesign all the glass containers, milk bags easily adapted to new measurements, making them the ideal choice.