It is often thought that the family names of immigrants were changed at Ellis Island. How often did this really occur? If it occurred, what was the intent? What were the primary causes of name changes?

by JerikTelorian

In The Godfather Part II, a young Vito Andolini's name is changed to Corleone (the date is stated as 1901). Other media and cultural lore has portrayed name changes at the island too.

Did this practice occur, and if it did, under what conditions was it sanctioned?