Previously I have talked about depression era posters and Soviet propaganda posters. Thomas Hart Benton was a depression era painter and muralist from southwest Missouri. Growing up in St. Louis, I was exposed to his art from a young age. His shading brings the people in his paintings to life. He often depicts scenes of work, as suits the depression. (Both of the images in this entry can be found on Wikipedia.)
Cut the Line (Wikipedia)
If you for some reason find yourself in Jefferson City, Missouri (unlikely), the capitol building has many of his murals. Then stop by Central Dairy, where you can get a pile of amazing ice cream for very little $. Then you have seen all there is to see in the illustrious capitol.
The 20-40s really seem like it was a golden age for illustration. Color photos were not as vibrant as they are today, yet mass printing existed. Thus, beautiful and stylized portraits of life were used in advertising and propaganda (Alphonse Mucha did lovely art nouveau illustrations for advertisers since the late 1800s, I wrote about him here). Many of us have seen the posters created for the Great Depression and WW2 by artists such as Thomas Hart Benton.
When I visited the Czech Republic, Budapest and East Berlin, I was struck by their propaganda posters from the same period. There was such a contrast between the lovely illustrations and the content that we would likely find oppressive. It can be a window into history to understand how people chose (or were forced into) their path. For good collections of Czech or CSSR Propaganda, check out the Communist Musuem in Prague and Checkpoint Charlie in Berlin. The featured image for this post is the poster for the Communist Museum; one of my souvenirs from Prague are some nesting dolls with this design.
To have more we must produce more (Wikipedia)
The Czech, Hungarian, and German posters seem hard to find, and I only know the languages a little (if anyone knows good sources, let me know!) I find the role of small countries in the early 20th century especially interesting since they are underrepresented. The countries of central Europe endured many of the worst hardships during the 20th century. There are many sources for Russian propaganda posters: