And if you're thinking about the price of labor -- well, it's only about 10 percent of what it actually costs to produce a car. And at the moment, labor's still cheaper in Mexico anyway. That's why the Brookings Institution, which did an incredibly detailed report on Tennessee's auto industry last year, emphasizes that low wages aren't what states should be focusing on.

"The U.S. is going to have to compete on productivity, great quality, and innovation," says Mark Muro, director of Brookings' Metropolitan Policy Program. "Cost is not the only element of competition between places now. Competition is real, it just will be waged over the next decade on a much broader variety of dimensions."

That means a constant supply of well-educated and happy workers, which unions can help with. It also means robust infrastructure, which can only be paid for through a healthy tax base of people making a decent living. Without those things, no amount of wage suppression will make a difference.
Tennessee was afraid of the United Auto Workers. Here’s why it shouldn’t be.