I have 200,000 addresses in MD for which I need zip+4.
I am searching for an address locator for ArcGIS or a (free?) batch service that will output 9-digit zip (Zip+4) from address. I have already geocoded these addresses so I have lat/long from street or point address for a good portion.
I do have Esri Street Map Premium service and that allows for 9 digit zip to Lat/long but not Address to Zip+4. Odd. There is a "PostalExt" field in the output but i does not populate. very annoying. Reference data must be available for the boundaries (or at least centroid) for this data but it is not available for use in the street map premium FGDB.
Since I'm only interested in one state (MD), my plan was to reverse geocode all permutations of possible 9 digit zips (about 6 million) to get their lat/longs, but it seems quite dirty to do a spatial join on these points to the previously geocoded 200k address points.
Any other suggestions very welcome. I have seen that USPS does not have or make available polygons for zip+4 but you can purchase tables of the address ranges per +4. Not sure if that would even be that helpful for me.