First of all, it is not necessarily correct to say that Americans did not want immigration during this time. Some Americans did want immigration just as some Americans want immigration now. For example, the leaders of big business were generally in favor of immigration because they needed workers for their factories. Thus, we cannot say that all Americans were opposed to immigration.
However, many Americans were opposed to immigration. One reason for this was the fact that the new immigrants were from the “wrong” part of Europe in the minds of the nativists. Many Americans of the time believed that people from Southern and Eastern Europe were not really white. They felt that they were of a different race from the Germans and the English and other Northern and Western Europeans. They felt that these new immigrants were, in other words, racially inferior.
Secondly, many Americans did not like the new immigrants’ religion. Many of the Eastern Europeans were Jews. Most of the people from Southern Europe were Catholic. These were religions that were looked down upon by the Protestants who made up most of America at the time.
Thirdly, many Americans felt that the immigrants were too politically radical. At the time, many people, particularly in Southern Europe, were coming to agree with the ideas of socialism and anarchism. They brought these ideas with them to the US. Americans were strongly opposed to these ideas, especially when they led to such things as labor strife in the US.
Finally, many Americans simply thought that the immigrants brought too many problems to US society. This is much like our attitudes to immigrants today. Nativists felt that immigrants were prone to commit crimes. Some felt that immigrants were taking jobs that belonged to people born in the US. They felt immigrants were more likely to be drunkards. They believed that immigrants had inferior cultural habits.
All of these things caused many Americans to have nativist feelings against the immigrants. These feelings eventually led to the creation of laws banning Chinese immigration. Later still, in the 1920s, they led to laws restricting immigration from Southern and Eastern Europe.