Zip codes can and do cross both state and city boundaries in some cases. That's not true of zip+4 but most people don't know their extra 4 digits. Then there i

Zip codes can and do cross both state and city boundaries in some cases. That's not true of zip+4 but most people don't know their extra 4 digits. Then there is the expected rhythm of filling in the form as city,state,zip so putting zip first throws people off. I did a form once where we put the country above city/state/zip so we could do the wording for those more appropriately (e.g., switch to "postal code") and even that was annoying to many testers.