These two regions were singled out because many Americans held the perception that individuals from southern and eastern Europe could not be assimilated properly into the culture of the United States. Their languages, customs, and religions were thought to be too different from those of preceding generations of immigrants for full scale integration into American culture. The fear was that these newer immigrants would always be "hyphenates,” or citizens who would call themselves, or be called by others, by such hyphenated names as "Polish-Americans,” "Greek-Americans,” and "Italian-Americans.”
Beyond the fear of being swamped by unassimilable immigrants from eastern and southern Europe was the fear that these immigrants’ increasing numbers would depress wages for American workers. In addition, some people feared the potential of the rising political power of the new class of immigrants.