This is a webmap of a geographic database I've been working on. This map will have points for every ruin, every historically significant industrial structure or site, every 19th century insane asylum, industrial reuse project, odd small town, abandoned place and others in the conterminous 48 states. At present it can be searched has a selection of pre-set point filters and provides pop-ups that lead to a Google map and or more information. It was made using Openlayers and Openstreetmap. I will be updating this map periodically.
In the above map, I've tried to represent the population change of counties relative to the population change of the country at large. The challenge was to find an algorithm that would consistently represent this relationship across any arbitrary length of time. I'm not sure I succeeded but I thought the results were interesting. The map lets you pick a start and stop census year. You can then calculate and represent a quotient for each county. This is: percent change in county population divided by percent change in US population. You can also calculate the number of standard deviations a counties' population change was from the mean population change. Since some counties, especially in the early 1800s, increased in population thousands of percent, this didn't always work very well. To get the distribution closer to normal, I adjusted very high values down. Both standard deviations and quotients can be animated in ten year steps from 1820 to 2010. This map was made with Mapbox.js and uses slightly improved census data from the NHGIS.
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.