I just came across this fabulous piece from the IWW campaign to ban child labour, I assume, in the US. I know very little about the actual piece, but I can only guess that it was done pre-1938. That was the year child labour was officially banned in the US under the "Fair Labor Standards Act"--and by that point the IWW had been in decline, as far as I know, after repeated red scares and crack downs on the part of the government. My best guess is that this from sometime in the 1920s.
Nonetheless, a great piece. Don't you wish union posters were still this honest?