How would you go about designing a system based on arbritary zones? Think of the American states - basically the whole map is carved up into irregular zones. Then again another one might show a salesmans territory, TV stations coverage area etc. I need to be able to retrieve the current GPS position and determine which zone I'm in. I can't use an address/zip lookup - its purely based on the lat/long point. So the data structures which define the enclosing boundaries must be flexible enough to provide fairly accurate positioning. As a bonus, I'd also like to be able to render these zones on the map, maybe with different colors. Any tips/pointers to anything close to this would be very welcome, thanks.