When was the last time you bought a car that wasn't manufactured in the U.S.?
I seem to recall companies like Honda - companies that are not U.S. based, mind you - building factories in America because, well, cars are friggin' huge. It's expensive as hell to ship them across an entire fucking Ocean and then drive them cross-country. It's cheaper to pay good wages in America than to pay lesser wages in other countries and ship it out.
Yeah, yeah, there's still plenty of companies that import, but as stuff like Chrysler and whatnot collapse I'm sure that there will be foreign companies looking to snap up fully-functional plants so they can save on shipping. Remember, having a plant in the states gives you access to most of North America by land.