The Library of Congress has photographed and made available online 1,900 World War I posters created between 1914 and 1920. The majority of the posters are from the United States, but the collection also includes posters from Canada, Great Britain, Germany, Austria, Australia, Belgium, Italy, the Netherlands, and Russia. Here’s some background from the introduction to the collection:
During World War I, the impact of the poster as a means of communication was greater than at any other time during history. The ability of posters to inspire, inform, and persuade combined with vibrant design trends in many of the participating countries to produce thousands of interesting visual works. As a valuable historical research resource, the posters provide multiple points of view for understanding this global conflict. As artistic works, the posters range in style from graphically vibrant works by well-known designers to anonymous broadsides (predominantly text).
The Library of Congress Prints & Photographs Division has extensive holdings of World War I era posters. Available online are approximately 1,900 posters created between 1914 and 1920. Most relate directly to the war, but some German posters date from the post-war period and illustrate events such as the rise of Bolshevism and Communism, the 1919 General Assembly election and various plebiscites….
The poster was a major tool for broad dissemination of information during the war. Countries on both sides of the conflict distributed posters widely to garner support, urge action, and boost morale… Even with its late entry into the war, the United States produced more posters than any other country….
All of these posters are in the public domain the United States, and you can download free digital files directly from the Library of Congress website or purchase photographic copies. Here are two of the posters:
There’s lots of other great stuff in the LOC’s Prints and Photographs Division–historic photographs (including Mathew Brady’s Civil War photographs, Ansel Adams’s Manzanar War Relocation Center photographs, and many newspaper and magazine archives), fine prints and posters, baseball cards, cartoons, and so on. Here are links to the online catalogue and the collection and subject overview, so go browse. (An important note: some of this material is still under copyright. See the LOC’s rights and restrictions information for details and the copyright status of specific collections.)