Zip code/proximity/state relationship

[beetle]

Hello all

I soon will need the capability to search my DB for users within adjacent (or relatively close) zip codes. I've done some searching (and will keep doing so) but haven't found any good data source for this yet. I'm certain I can work all the logic, but I need the data that tells me what ZIP codes are in which states, and which Zip codes are in proximity with one another.

Any clues? Sources? Experience?

Thanks.

[Spookster]

http://www.zend.com/tips/tips.php?id=249&single=1

http://zipinfo.com/


http://www.cryptnet.net/fsp/zipdy/index.html

[beetle]

Thanks Spookster. During the time-gap between my post and your reply, I have found what I think will suit me best. First of all, I need a radius search, not just a distance calcuator. I've got my hands on the trigonometry I will need to do this (haversine forumla)

www.zipinfo.com looks interesting, but I think we will purchase from www.melissadata.com. I just seem to have more trust for a site that doesn't look like a (very old) FrontPage theme. Besides, the cost is identical. Also, I don't think my boss wants to rely on a 3rd party server for part of our functionality.

thanks for your time!