It doesn't contain my zipcode/city combination. My zip code spans across a city line, and the json file only has the OTHER city in it.

For what it is worth, this is the ZIP code data as according to the USPS. The scripts simply create the JSON file for you by calling the USPS API for every zip code between 00000 and 99999 (plenty of holes in there) and recording the response if there is one.