PHP - How can I lookup the Zip Code using the City & State

Question

I need to lookup the Zip Code for a list of addresses (which include the city/state). Is there a master zip code list for download (that is free) or are there any web services that will return the full postage info for an address.

Ie, lookup query: 386 Bread & Cheese Hollow Rd, Northport, NY ====> 386 Bread And Cheese Hollow Rd, Northport, NY 11768

Thanks!

Answer 1

I've seen zip code databases that can be purchased. Address correction services are available through major shippers like UPS, FedEx and the USPS, but I don't know if those services are free.

Answer 2

There's an API for that.

http://developer.yahoo.com/maps/rest/V1/geocode.html

Answer 3

This is a free library that you can download and use locally, without having to rely on a third-party API:

http://zips.sourceforge.net/

Answer 4

City and state alone are insufficient to properly determine ZIP codes. See the explanation at http://semaphorecorp.com/cgi/zip5.html

Instead, determine ZIP+4 from address, city, and state using CASS software.