Note: this fork is not maintained. Please reference the original project of which this is a fork. This stackoverflow post also contains some useful resources.

It is important to recognize the limitations of a project such as pyzipcode. Zipcodes are not areas but instead refer to the addresses on a mail delivery route, or else the location of a post office. Converting them to polygons is hypothetically possible, but it is open to interpretation. Technically, only mailing addresses have zipcodes and the space between mailboxes have no zipcode. In practice, mail routes follow roads, and one can create polygons by drawing boundaries around the roads and addresses of a route, but the resulting polygons are often non-contiguous. Computing the centroid of this polygon (as pyzipcode does) is extremely fraught; it is quite likely that the centroid is not even within the polygon! Zipcodes also change fairly frequently as postal routes change and new addresses are created, so any data source which is not updated regularly quickly becomes useless.