Re slavery, I learned something today during a presentation at Colonial Williamsburg. I only caught part of the story as we were just resting under the giant oak for a bit. Anyway, during the pre Revolutionary times slaves could buy their freedom if they could afford to. They still needed permission from the Colonial Governor and pay a "Freedom Tax". The tax was good for 6 years and the rate increased incrementally every time. If they couldn't afford the tax, back into bondage.
Interesting that part of history never came up when we were taught in high school 50 years ago. I doubt that it comes up today.