You'll be amazed how many Americans aren't aware of that either. Even Jewish folks ignore it. I had to tell the younger members of my family about the racism we Irish Americans suffered and some were in disbelief. We were called the N word, so did Italians, Polish, etc.
When President Coolidge said "America must remain American" we was talking about us.
The KKK was very powerful in Maine not because of blacks that "needed to be kept in place" but because of Irish Catholics from Boston and specially the fear of Quebecois invading from the north to destroy protestant democracy.
Terrorism is not new in our country, Anarchists practiced it in the late XIX and early XX century. Most of them were Jews, Eastern European, and Italians and their communities were instrumental in pointing out the bad apples. Sound familiar!
History rimes!