According to the Gothenburg, Sweden, Passenger Lists, Erik`s destination was Mapleton, Monona, Iowa.
He departed Gothenberg 18 March 1890, on the ship Livorno to Hull, England.http://search.ancestry.com/iexec?htx=view&r=an&dbid=...
I do not find him in the 1900 census for Mapleton, IA.
Do you have any more info on him? you say Erik is your great grandmother`s uncle, would that be her father or mother`s brother? any other family members, Father & mother, wife?