*Note that map data is drawn from the US federal census reports. Census data on free and enslaved individuals is not comprehensive and sometimes misleading, highlighting the problems of relying solely on census data and the importance of drawing upon a diversity of source material. Sources used to construct the 10 Million Names database are broader and deeper.
Hacker, J. D. (2020). "From ‘20. and odd’ to 10 million: The growth of the slave population in the United States." Slavery & Abolition, 41(4), 840–855. https://doi.org/10.1080/0144039x.2020.1755502