A Map of County Population Density From 1820 to 2010
This map (above) is pretty simple at the moment. It shows the population density of counties at any census from 1820 to 2010. You can animate the map in 10 year increments from 1820 to 2010. I will add expanding rail and highway networks to this map in the future. I also plan to link my database of historic industrial sites to this map. This map was made with Mapbox.js and uses slightly improved census data from the NHGIS.