This used to be up on the old Consolidated Aircraft Plant in San Diego during the war. A lady near my parents was selling it at her garage sale and she got it from her mother that used to work at the plant during the war. Because the poster was old, the lady had it set on a tin panel to try and preserve it.
It was aimed at keeping days off at a minimum so production levels wouldn't drop at the plant.

ack-ack
Hey man not trying to to burst your bubble but, you should check the validity of it and I hope you didn't pay too much for it
World War II : United States Home Décor >Other >Home Front

You Think War End Soon? Metal Sign
You Think War End Soon? Metal Sign
Replicating one of the anti-Axis messages used to motivate workers on the U.S. home front during World War II, 24-gauge steel sign is hand distressed to create the look and feel of aged metal and paint. Measures 8"x 14" and includes mounting holes.
#M600328
Price: $16.95
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http://www.militaryissue.com/product_info.po?ID=8457&product=Home+D%C3%A9cor&category=other&subcategory=Home%20Front