Why were some Americans unhappy about the group of immigrants who came to America in the 1800s

The flood of immigrants began to alarm many native born Americans. Some feared job competition from foreigners. Others disliked the religion or politics of the newcomers. During the 1850's, the America Party, also called the Know-Nothing Party, demanded laws to reduce immigration and to make it harder for foreigners to become citizens. Although the part soon died out, it reflected the serious concerns of some Americans.