Also shows the correlation to slavery in the US as well http://www.smithsonianmag.com/history/maps-reveal-slavery-expanded-across-united-states-180951452/?no-is

Also shows the correlation to slavery in the US as well http://www.smithsonianmag.com/history/maps-reveal-slavery-expanded-across-united-states-180951452/?no-ist http://www.smithsonianmag.com/history/maps-reveal-slavery-ex...