Mark Perry sums it up nicely:
What are the main economic differences between right-to-work states and forced-union states (see map above)?
Not much really, except that compared to forced-union states, right-to-work states have had faster economic growth, lower unemployment rates, greater employment growth, higher state real GDP growth, greater growth in personal income, higher population growth, and greater home price appreciation. That’s all.
Also check out the ALEC-Laffer analysis that found that the two biggest factors in state economic growth is the personal income tax rate and right-to-work laws.