If you take this question worldwide, anyone who is forced to live and work under the direction of another person is a slave. Sadly, we have slaves today. Immigrants illegally brought into England, for instance, have been holed up, often in horrible conditions, and forced to work long hours for next to nothing.
And this is 2018! Such slave 'owners' are, of course, severely punished when their crime is discovered. So, in the US, there will have been cases like this in addition to the thousands of African slaves.
