The admin of a Drupal site enters and updates many addresses every day. For every contact and organization account on their site, they have a city, state, zip code, county, and region. Really, the address fields are just redundant information. Everything can be gleaned from the zip code. So, in an effort to become more efficient and reduce data entry errors, the client requested that the city, state, county, and region fields autocomplete by entering the zip code.