These files are fairly useful for other mapping purposes as well, since they consist mostly of a sequence of polygons that form the boundaries. The coordinate system is latitude and longitude, and each polygon has a group to list the name of the post office, the county, the population, and the host count from a crawl in 2001. Each file can be made to reference an external javascript file in which you can embed your own animation to manipulate the SVG.
Note: Mozilla 1.5 claims to have added SVG support, but I have not yet encountered an SVG file that it can properly render. Maybe someday...
Feel free to use these files in your own fun, but I would appreciate receiving credit for having created them. Enjoy...
There is also a simple map of the world, a map of the states, and finally a huge file of 48 states (13M zipped). This last file is probably too detailed to be useful.
Kevin McCurley created these.