Yes, ghettos predated this era, but this was the first formation of the American ghetto. See the edited volume I referenced in an earlier comment, it gets into some of the ghetto formation that predated American ones. The earliest were in Italian city states (around the 14th century) and they were Jewish ghettos, as Jews were used for economic exploitation while also being considered symbolically corrosive bodies. You see, ghettos do not form in cities unless there are 2 conditions met. First, a group must exist that is perceived to be in need of separation (typically due to fears these groups are physically tainted in some way). Second, the group must be attractive to the interests of capital/profitability. Without both conditions being met, the perceived corrosive group is simply banned from the city or it at least gets the message that there is no home for them there and they move along. But in situations when capital can use a “corrosive” group’s labor to enhance profitability, then we see ghettos form. In the Italian city state Jews became the traders who traveled the Silk Road for Catholic elites. Catholic doctrine of the day deemed money lending and usury as sinful, yet elites still desired some of the goods they could get from the near and far east. They were status symbols that functioned to distinguish elites at home from those below them in the stratification system.
