I'm curious as to why the increase in California? The decline in the midwest makes sense, as we are losing a lot of our industry to the south and to other countries... but what sectors are these gains being made in in California?
California tends to be more affluent than many parts of the US...
Is it possible what we are seeing is a greater unionization of affluent people while seeing a decline in unionization amongst the poorer workers?

It seems like the information is a little lacking in details.

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