Almost all search engines ignore the keyword meta tag. In fact, you should remove that tag altogether. So, your best bet is Google places. Another on-page tactic is to pick a page and add the zip codes with an appropriate phrase in front of each location/zip code.
![maximlib maximlib](https://moz.com/avatar/large/6/m.png)
Posts made by maximlib
-
RE: Proper way to include Location & Zipcode Keywords