This table contains all of the zip codes valid within Wisconsin and at least the first three characters of zip codes that are valid outside of Wisconsin.
Some entries also give city and state information when it is unique for a given zip code.
This is the one and only key field. There should be an entry for each valid five digit zip code within Wisconsin. For non-Wisconsin zip codes, there should be a record for each valid set of first three characters. In other words there would be one entry for all zip codes starting with any particular three digits. Picture is 3 characters.