Immigrants were a convenient object of attack, because as nonvoters their interests could be safely ignored. It was easy for politicians to play upon the xenophobia that has erupted from time to time in American history: the anti-Irish prejudices of the mid-nineteenth century; the continual violence against Chinese who had been brought in to work on the railroads; the hostility toward immigrants from eastern and southern Europe that led to the restrictive immigration laws of the 1920s.

— A People's History of the United States by Howard Zinn