What you are looking at is an overlay of the 2008 Presidential Race results. Blue counties supporting Obama, and black dots from a circa 1860 map depicting where every 2,000 bales of cotton were being produced. In other words these are areas of the south where slaves where clustered just prior to the Civil War.
148 years later these families which apparently decided to stay put in the deep south cast their ballots for America's first black president. The long black line.
h/t to
StrangeMaps and
Allen Gathman
Slave trading house image courtesy of
Life Magazine
