With an office full of regular NPR listeners, it’s awesome to see NPR Digital Media launch the new I Heart NPR Facebook app with a listener map prepared using TileMill, our open source map design studio. The app asks users to choose their favorite station, and their entry is indicated on the map. Each point represents an NPR member station and the size of the point indicates how many people selected the station as their favorite.

The point data is processed and rasterized into tiles using TileMill, making the map very fast and capable of showing thousands of radio stations without bogging down the browser with the task of drawing each point on the fly. After the tiles for the map are rendered, they’re exported to MBTiles format.

The map is interactive, allowing you to hover over a point to see the station name and the number of fans. For us this is a proving ground for a new mechanism for producing, sharing, and displaying interactive maps. The design of the mechanism allows you to interact with thousands of points or complex polygon data at incredibly high speeds. The next release of TileMill will allow you to author your own interactive tilesets with hover and click behaviors and export them to MBTiles format. Both TileStream and the MapBox app for iPad will soon be capable of displaying the interactions to users.

We’re especially excited to be working with the NPR team to host the MBTiles files in a highly available TileStream server environment where the tiles are served through a CDN. The map is refreshed with the latest data on a regular basis. This is allowing us to test our new infrastructure for what will become a hosted TileStream Pro service, which we’ll be talking about more in a few weeks.

Have a look at the app and the maps, and support public radio.