Optimal routes from the center of U.S. to all counties
The map and the animation show optimal routes by car from the geographic center of the contiguous U.S. to the center points of all counties. One starting point and roughly 3000 destinations. Some people have commented that this looks like slime, some say that it looks like electricity.
Original idea for this came from the Roads to Rome project by Moovel Labs.
Data
© OpenStreetMap contributors via Graphhopper routing API
Tools
Python (you can find the scripts here), PostGIS, QGIS with Time Manager plugin, GIMP
Tutorial
I have written a tutorial on how to do this kind of animation yourself and you can read it here.