If you take a historical map of the US slave population and overlay that with the concentration of the black population in the Southern US today and then overlay that with a map of median income, avg life expectancy, education, etc. you'll see a very clear connection.
I agree that a more level playing field along income lines would create a more fair and just society, but you're talking about a problem that the free market cannot solve and would lead to an argument for a very different type of economic model. I'm all for it, but it's a tough sell in the US.