I am looking for shapefiles (or, any other GIS format) or csv/excel files on 9-digit Zip codes for the US (NY and MA states), which includes the regular 5-digit zip codes plus the 4-digit courier/routing codes. I found the 5-digit zip codes via multiple portals (including the census bureau data) but not the full 9-digit dataset. Is there a way to access the 4-digit courier codes or the full 9-digit dataset? Some private delivery services make them available for a very high fee. I am looking for open data alternatives as my funding does not cover data purchasing. Any direction will be much appreciated.
Thank you.
