While using Esri's zip code data, I've noticed that there are a lot of invalid zip codes that begin with three zeros (00084, 00041), does anyone know why this happens? It is challenging to make joins to valid zip code data when esri gives out zips that don't exist.
government? overseas? I am sure there are a number of 'special' zip codes like there are in other countries
Canada even has a seasonal one H0H 0H0
I kind of just figured this out on my own. There are still many remote locations in the US that don't technically have a zip code because there are no addresses in that area. To make up for these gaps, Esri's census data uses one of two methods. They will either extend an existing zipcode's area out to compensate for the missing one or create a new one to fill in the gap. These new zip codes usually will begin with two or three zeros, and contain no addresses according to the USPS. They are simply there to fill in the gaps of the shapefile.