Data Visualization: the spread of slavery throughout the US over time

[Brian Howell]

Article: http://www.citylab.com/housing/2016/04/a-new-way-to-map-the-spread-and-decline-of-slavery-in-the-us/480000/

Map site: http://www.radicalcartography.net/index.html?slavery. 

Check out the cartographer's other maps, like the astrogeography of the Moon. Some of them are really cool.