The primary data used for this visualization comes from the ICPSR's tabulations of historical data sets: Haines, Michael R., and Inter-university Consortium for Political and Social Research. Historical, Demographic, Economic, and Social Data: The United States, 1790-2002. ICPSR02896-v3. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2010-05-21. http://doi.org/10.3886/ICPSR02896.v3

Historical County boundaries are taken from the Newberry Library's Atlas of Historical County Boundaries: Siczewicz, Peter. U.S. Historical Counties (Generalized .01 deg). Dataset. Emily Kelley, digital comp. Atlas of Historical County Boundaries, ed. by John H. Long. Chicago: The Newberry Library, 2011. Available online from http://publications.newberry.org/ahcbp.

This site includes color specifications and designs developed by Cynthia Brewer (http://colorbrewer.org/)

It makes use of Javascript frameworks D3 (d3js.org) and jQuery (jquery.org), as well as the Bootstrap library. A few CSS styles are borrowed from Elijah Meeks' project d3.carto.map.

The slideshow on population density uses scans of the Census atlases from David Rumsey historical maps.