what if I just want to have US zip codes...

I think you can edit the module. Remove all zipcode.*.inc files, except the zipcode.us.inc file. After that you have to edit the zipcode.module file and remove there all options except the us-options.

The way to do that is what explained Bambusstock but there are no need to do so : just select the country you need in the content types to create the page template you need

I've hacked both Zipcode and Phone modules to eliminate all but the US and Canada, as Bambusstock suggest.
All you need to do to delete or comment out the lines in the array definition around line 31 in both modules.

Thierry, my main reason for doing this is so that I don't have to scroll past 30 phone options and 30 postal code options that I'll never use, every time I go to create a CCK field type.

Altogether, two very useful modules - and thanks very much for making them!

It would be really nice to have a cleaner way to turn off the countries that aren't needed.