Very strong correlation between Right-to-work states and Republican controlled ones

Click on figures to enlarge them.

Note that there are only four states that don't fit the pattern. 

Virginia is a right-to-work state but it has a Democratic governor and a Republican legislature.

Iowa is a right-to-work state but Democrats only control one house of the state legislature.

Wisconsin isn't a right-to-work state but it has clear Republican control of the state.

Ohio isn't a right-to-work state but it has clear Republican control of the state.

Besides those four anomalies, all the other red states are right-to-work states and all the right-to-work states are red states.  Still even these anomalies aren't that far off, Ohio almost became a right-to-work state and Wisconsin has changed the rules for public employee unions so that people can't be forced to join a union.  And Virginia was close to having Republicans in control of the state.  Iowa was also more red than blue.

Thus the two right-to-work states can hardly be classified as blue states and the two red states are hardly solid anti-right-to-work states.

The question is one of causation.  Do already trending red states support workers making the their own decisions on whether they should join a union?  Or do right-to-work laws make it so that unions can't raise a lot of money from people who don't want to be union members so that the unions can support Democrats?  I don't know of anyone who has studied that question carefully.

Here is a list of states ranking them by the percent of workers in the state who are union members (Republican controlled and right-to-work states are in bold).