The word ghetto was invented in Italy in the Middle Ages where Jews were allowed to live - they weren't allowed to live with the majority Christians. This was a large favour to the Jews because in other places in Christian ruled Europe they were forcibly converted, killed or expelled.

Similarly, ghettos in North America were created because the majority communities wouldn't allow the new immigrants to live with them. Hence the presence of little Italies, Chinatowns, Jewish ghettos, etc all over North America.