In the 20s the USA was considered isolationist, America for the Americans so when a influx of immigrants came in they faced harsh feelings from the born and bred Americans.
This can be confused with racism, if what happened in the 20s happened now it would be but there is a difference between not wanting someone in your country based on race and not wanting someone in your country based on the times ideals. We need to stop judging people from over a century ago like we would today, it was a different time, different ideals and different motives. I am not discounting the presents of racism obviously but pointing out the cultural influences at the time.
