The USPS already has this information The USPS does have this information, but when I checked a year or two ago, you either have to (1) agree to use the inform

The USPS already has this information The USPS does have this information, but when I checked a year or two ago, you either have to (1) agree to use the information only for purposes of mailing packages, per their TOS; or (2) pay them, e.g. something like $500 for a list of all five digit ZIP codes plus associated cities and states (the "City State File"). Corrections very welcome! Edit to add: As philfreo asked, I'm also very interested in knowing where the data in zipcodes.db comes from.