postal/zip code

Philippines
January 12, 2007 5:02am CST
i'm really wondering what does the additional 4-digit means in US postal codes. say for a new york postal code 10001-4121, i know that the 10001 is the zip code but whats the 4121 mean?
1 response
@seenoreen (559)
• Philippines
12 Jan 07
Based on my research, it says that the last 4 digits are the add on code for the P.O. box. I hope this helped.