The USPS-Selling Zip Codes or Public Information?

An Anonymous Coward asks: "What is the definition of public information? Would you think that the official names of cities and their Zip Codes would be public? In a way it is, because the USPS will allow you to do a lookup against their online database. The tricky part is trying to get the entire list, then the USPS wants you to pay. They could very easily provide the information in any database or comma delimited format on their website but they choose not to. Why? They are making a lot of money reselling this information to companies who repackage it and then sell it to the public. " Hmm...good point. But are zipcodes really public information?