The correct answer to this open question is the following.
Nativism was the belief that descendants of English settlers needed protection from other immigrant groups.
The English descendants that lived in North American feared the migration waves from European countries and Asia. That is when the idea of Nativism developed. The belief that Americans had to be protected from these immigrants' culture, traditions, and customs. American citizens started to demand government actions to put a stop to migration. This was a negative reaction to immigrants that "flooded" large cities such as New York.