I'm using php with mysql. I would like to do searches on my site using zip or postal codes as criteria. Can anyone recommend where I may find a listing of states and their zipcodes and anything similar for Canada, Australia or the UK?
[RESOLVED] Search by zip or postal code
Just google for "zip codes" and states, you should be able to find some free listings. For a rough zip code assignment per state, try http://en.wikipedia.org/wiki/List_of_ZIP_Codes_in_the_United_States. If you need more detail break downs, like to the city and town levels, then you might have to shell out some money 
I saw a database insert sheet with zip codes for about a half dozen states and it was a huge, huge file. The guy that had it said you'd have to break it down into smaller chunks to upload it to the database. If this was just for a few states I can't image what it would be like for the entire country.
It would probably take a week to get it all in the database. Not only that but they often change the zip code areas and add to them, so you'd have to stay on top of that too.
For UK post codes you can buy the PIF database from royal mail.
If you want full address data then the PAF database is also for sale, it lists almost every address in the UK, but it costs a lot.
thanks guys