The most recent release of Cartographer.js supports county-level choropleth maps. This was the number one requested feature for Cartographer and I am delighted to finally be able to offer it in an official package. Many thanks to Ben Cohen and Xanthippe Wedel for making this a reality. The image above is a snapshot of the California county populations map.
Counties are drawn using the same efficient polygon encoding as states, and they can be easily referenced by name. All color schemes and other choropleth map features work for counties just as they worked for states. Click here to download Cartographer.js v0.4 with full county support.
Some additional notes about this release:
- Loading all US counties into a Google Maps is quite a challenge, and it’s recommended that you only use Cartographer’s county mapping facility for a few states at a time unless you wish to stall out older browsers. Google Chrome handles the large datasets gracefully, if slowly.
- Adding counties increases the filesize of Cartographer.js significantly. If you don’t need counties, feel free to use an older version for now, and this should be fixed in an upcoming release.