It is Italian.
In the sixteenth century, a number of European cities decided to force all the Jews in their precincts to live in separate enclosures within the city, walled off from the rest of the citizens. The section in Venice in the 1510s was near an iron foundry and picked up the word ghetto for a slang term for the district. In 1555, when Pope Pius IV issued a truly hateful ruling confining Jews to a tiny neighborhood in Rome (with a clear indication that the Roman policy should be enforced throughout Europe), he used the word ghetto.
Since then, the word ghetto (in English) has broadened slightly to mean any ethnic enclave, frequently one in which residence is compulsory. While most ethnic groups chose to live near each other in the cities, there were also laws (or deed restrictions) written to prohibit blacks from moving into specific neighborhoods, effectively limiting them to their own ghettoes.
Throughout the twentieth century, blacks were confined to specific neighborhoods and (generally underfunded) schools. They were subjected to “last hired; first fired” discrimination in industry (often forced to surrender their jobs to immigrants) so that their overall wealth, never great to begin with, shrank in comparison to that of their white neighbors. They were barred from entering many unions, and so were not able to demand the same pay as their white counterparts. A second generation European immigrant, generally lacking an accent, could pick up and move to a new neighborhood, and not be denied a house. If there was a local prejudice against a particular ethnic group, the immigrant could change his name to that of a more acceptable ethnic group and simply blend in. Generally, blacks could not do the same thing, (although there are many stories of lighter colored blacks taking Italian or Greek names to “pass” for white and escape the ghetto).
When the U.S. began to pass social support legislation, much of it was written with a moralistic “we won’t support a lazy man at home” attitude, so much of it was written that it could only be used by single mothers–putting pressure on unemployed/unemployable men to abandon their families so that their kids could eat.
Despite the above conditions, the black community strove hard to adapt and they did build up a middle class. (It should also be noted that a number of the race riots of the early twentieth century were white-on-black riots intended to destroy black middle class neighborhoods, setting an example that if blacks got too well off, they would have it destroyed in front of them. Tulsa, OK, Springfield, IL, and several other locations come to mind.)
Once the laws permitting discrimination were overthrown, (with judicial rulings occasionally being followed and equal housing laws occasionally being enforced), the black middle class began to take advantage of the opportunities to escape their ghettoes, but the changing dynamics of American cities–in terms of the locations of jobs and the presence of transportation–left far too many blacks in the ghettoes.