Come on, how do any of us know what states really had slavery and which didn't. I for one don't believe 80% of what I read in schoolbooks or anywhere else for that matter. How does anyone alive today know what really went on over 100 years ago? They don't. Have you ever played telephone? You go around in a circle of 15 or 20 people and by the time the original message gets back to the first person it has usually changed drastically, and that is only in a few minutes time with a few people. Imagine how much things get skewed over a span of 100 plus years and millions of people.
It's just like saying no two snowflakes are alike, they cannot prove that. They would have to examine every single snowflake that has ever fallen in the history of the world and compare them to all the other snowflakes. Impossible. To me this map holds no merit whatsoever. But I am naive, because I don't believe everything I hear.
