[scott_karana]

Actually, I suspect the law was in place more to entrench existing Canadian factories than promote new ones. (eg, 1 or more of the 3 cars were already made in Canada)

The bridge between Windsor, Ontario and Detroit, Michigan is likely the most-travelled on the continent, carrying 25% of US-Canadian trade, and $13Bn of assets, mainly due to the large auto industries of both countries.

(The US domestic brands are predictably huge, and there's also Magna, the 3rd largest part supplier in the world http://en.wikipedia.org/wiki/Automotive_industry_in_Canada)