A lot of those states have low unionization percentages. Michigan is at 17% or so, and I think only New York has a higher percentage in the lower 48 states (at 21%). Of course, in New York this is mostly in construction and trades because the Mafia runs a great deal of real estate development, and New York's unemployment rate is more a function of the fact that Wall Street is doing well.

However, look at Colorado, which has only 6% or so participation in unions. The lack of "right to work" provisions doesn't affect Colorado as much.

It's very clear that Michigan's unions hurt it. America still makes cars, but Michigan makes a lot fewer of them than it did back in the 1970s, for example. There is a direct correlation between the unions and the destruction of Michigan's automotive industry.

The argument that factory workers make less without unions is true, but in most cases there is little to no difference after union dues are subtracted. As a result, workers take home roughly the same amount of money but the employer doesn't have to support a union.