A few weeks ago, I presented at the Tableau Fringe Festival EMEA about how Abraham Lincoln used the 1861 U.S. Coast Survey Map to help him understand slavery in the United States. This map, produced by the US Coast Survey in 1861, drew on census reports from 1860 – the last year that the US government collected census data on slaves. The map shows the prevalence of slavery by county, with darker shaded counties representing a higher percentage of slaves and lighter shaded counties a lower percentage.
It drew on census data and used groundbreaking cartographic techniques (choropleth maps) to visually depict the four million Americans held in bondage in the Southern states. The map revealed which counties had the highest concentrations of slaves, as well as which parts of the Confederacy might be the least committed to the institution.
Yesterday, Spencer Baucke (photo, right) recreated the 1861 Coast Survey Map in Tableau and it was selected as Viz of the Day. Below is a screenshot of Spencer’s map and, if you click on it, it will take you to Tableau Public where you can interact with it.
Congrats to Spencer for being selected as Viz of the Day and for continuing this story along.