Why did many Americans think that the new immigrants were to blame for America's society problems?

There was a Russian revolution in 1917. This alarmed America as many Americans had a fear of Bolshevism or Communism. What made things worse was that so many immigrants were coming into America From eastern Europe and Russia they were fleeing persecution (especially Jews) and from Italy they were fleeing poverty. Americans feared that the recent immigrants from Russia brang with them radical ideas. Americans began to see evidence of there fears when there was a wave of disturbance in America Lots of workers went on strike. The police did and looters and thieves roamed around. There were race riots. When the wall street chrash hit things were made worse as the jobs that were there were mainly taken up by the immigrants. this was because they were cheap employees and they did not need to have much skill due to new methods of production such as the assembly line put forward by Henry Ford.