I think one of the major targets of American propaganda during the first World War was Germany, which led to a lot of prejudice toward German-Americans. Oftentimes, German Americans tried to prove their loyalty by changing their names. They hoped this would show that they thought of themselves as American people rather than German people.
World War I American propaganda posters urged cooperation, encouraged proper war time behavior and motivated American workers. One of the most famous was the "We Can Do It!" poster featuring Rosie the Riveter, encouraging women to work in manufacturing plants to supply munitions and war supplies.
