100 Percent American

White, blue, and black top hat encircled by blue outline with blue and white text over red background. 

The jingoistic phrase on the button refers to a call to arms for the US's involvement in WWI.  A song, copyrighted in 1918, uses the same phrase.  In the song, there are obvious anti-German and anti-German speaking American undertones in lines such as "If in Kaiser Bill you trust, What's your business here with us."  

It was American policy to defame German-Americans and chastise German culture.  President Woodrow Wilson spoke out against the damage of hyphenated Americans, whose divided allegiances could not be clearly discerned.  The American Ambassador to Germany, James W. Gerard, had one of the most openly hostile view of German-Americans at the time.  He stated, after suggesting to "ship them back to the Fatherland," in a 1918 speech,"there is no animal that bites and kicks and squeals and scratches, that would bite and squeal and scratch equal to a fat German-American, if you commenced to tie him up and told him that he was on his way back to the Kaiser."  

The official policy led to actions ranging from interning German-Americans, to forcing them to take "loyalty tests," to the "expectation" that they would purchase war bonds.  German-Americans were the largest non-English speaking ethnic group in America in the late nineteenth and early twentieth centuries.  The highest concentration of German-Americans was in the Midwest.