title: How to find bounding boxes for Geocode radius Searches
body: <p>If I want to find all restaurants within a zip code, I can do a string search on the address, if I want to find all restaurants with 10 miles of a zip code, I need to do a location search. I have a database full of addresses and Geocodes should be no problem. But how do I compute the bounding box of an irregular shaped area, like a zip code, or city, or state or Metro Area?</p>
  
  <p>Is there a tool around that does this? is this information for sale somewhere? </p>
  
  <p>My initial solution is to create an estimate of the areas by searching for all addresses within them and deriving the simplest polygon that surrounds them and using that as a bounding box. However this seems a really brute force way to do this. Do I do this calculation for every city, state, and zip in my database and store it? How have other people solved this problem?</p>