Republican paramilitaries carried out a guerrilla campaign against British security forces as well as a bombing campaign against infrastructural, commercial and political targets. Loyalists targeted republicans/nationalists and attacked the wider Catholic community in what they described as retaliation.
In the 1880s, economic depression such as crop failure in Ireland, religious persecution such as persecution of Jews, search for jobs, were some of the reasons for immigrants coming to America. Closed immigration was not an issue at that period.