Well, depends. If you count the raise in worker welfare around the end of the industrial revolution in the 1910s/1920s, then yes. Data is very difficult to find, but check out some Bernanke articles and there are some references.
But this issue is at that time, workers where wanting normal workdays, prevention of child labor, safety standards so they don't lose their appendanges, etc. I think the problem is...striking when one makes $50/hr (all benefits included) is not going to garner the sympathy of America. If perhaps, they were striking because the employer wanted to force them to work 16 hours a day with no overtime (as was the case in the aforementioned time period) then there would be sympathy.
But, yes, around the turn of the previous century, unions were effective in improving the general welfare of the citizens. Now, I think, they have lost their way and there is really nothing to improve as many of the main objectives of unions are now written into federal law. I think unions should stick around just in case Congress tries to repeal the laws of worker safety, hiring practices, etc. but convert their role to more of a monitoring status.
However, who would want to give up the power?