"Keep him free--Buy war savings stamps" was one of many World War 1 posters used to encourage the purchase of bonds to finance the war effort.

During World War I, many branches of the federal government used posters to urge Americans to support the war effort. In a time without radio, TV, or the Internet, posters were an inexpensive way to deliver powerful messages to millions of people. The government hired well-known artists to create designs that unified the American people. Posters continued to be published during World War II, and new posters are still in production. The National Archives holds close to 20,000 posters produced by military and civilian agencies.