Yes...
American arms companies had plants in Canada.
No, Canadian war supplies, not US factories in Canada. Listen, I am glad of the US supplies, but most people think Britain’s supplies came from America only. They came from Canada and all over the globe, military and non-military.
Most Americans and British would be shocked to find Canada was our biggest supplier, as their help is ignored by both our nations. Canada never gets the credit it richly deserves.
British companies also had many plants in the US, so do you class them as ours or yours.