I was surprised to find that Portland, Maine, had ethnic neighborhoods. Italian, Greek, etc. I found out why when we took a boat tour around the area.
The boat guide took us by an island with abandoned building on it and explained that it was a "secondary" processing station when Ellis Island in New York would get backed up with immigrants. The boats would be diverted to that island for processing. The immigrants would be dumped out in Portland and would have to find their own way to New York City. Train fare was 50 cents a person and a lot of the immigrants didn't have enough money to get there, especially if they were large families. So they had to settle in Portland. Those of their nationality who were already there would help them settle in. Thus, ethnic neighborhoods were established.