I wasn't referring to prison labor although that is a valid discussion too. It's ironic that the "land of the free" only leads in incarcerated citizens, obesity, and diabetes per capita.

I also don't have a reference on hand. I listened to an NPR radio segment that blew my mind. There's a bunch of information from reputable sources but finding a specific number can be tricky. First of all, it's estimated because it's obviously unknown. Also, defining the "bounds" of slavery inherently changes the count. There is a fairly recent citation that states there are 400,000 enslaved people in the United States on any given day.

https://www.state.gov/what-is-modern-slavery/

https://en.wikipedia.org/wiki/Human_trafficking_in_the_Unite...

https://www.cbp.gov/border-security/human-trafficking

https://www.theguardian.com/world/2018/jul/19/us-modern-slav...