
Poster from the book "Agitate! Educate! Organize! American Labor Posters" by Lincoln Cushing and Timothy W. Drescher (Cornell University Press). The book spans the history of the labor movement in the U.S. Its 216 pages include 268 posters with accompanying text that provides interpretation and context.
Read more about the book at the Design Observer.
(Thanks to Nikos Tsoutis for the link!)