Other groups were mistreated for being visible different or for having a different religion, but this groups were largely protestant and you can't really tell them apart from Englishmen visually.
I'm afraid I'm only able to comment on the Germans. Germans were treated well for the most part as they were white and Protestant unlike the Irish or Italians who were Catholics. The Germans made up a large portion of the American population for a long time, today German heritage is the most common amongst white Americans. German culture was a lot more present in the US, until the First World War began there were thousands of German language newspapers however when World War I began there was pressure on them to conform to the greater American culture which most German Americans did. TR famously decried "hyphenated Americans".