By 1910, 13.5 million immigrants were living in the United States, which made up almost 15% of the American population. During much of the 19th century, immigrants were largely coming over from Western European countries. But around the turn of the century, home countries of immigrants to the United States were increasingly Eastern Europe and Russia. The global nature of World War I and an emphasis on Americanism and loyalty increased suspicion of "foreign-born" people.
This poster, advertising the Liberty Loans, lists 14 last names of different origins. The varying nationalities represented by these names, along with the words "Americans All!", implies that people from different backgrounds who live in the United States belong to this group we call "Americans," and that all can contribute.
The artist of this poster, Howard Chandler Christy, created some of the most recognizable posters of the World War I era, including "Gee! I Wish I Were A Man."