The total world prison population is estimated at around 11.5 million.

China is second - with about 1.7 million - however that's at a rate of about 1/5 of the US.

It's legal to force those 1.8 million to work in the US and some states don't even compensate - and in addition your something like 6 times more likely to suffer it if you black.

So you have a legally endorsed method of forcing people to work in the US, often without any pay - just saying if it quacks and walks like a duck.....