Or the first 3 digits, which denote which facility mail addressed to that zip code is sorted at. The default when you open the page is an interesting one- "005

Or the first 3 digits, which denote which facility mail addressed to that zip code is sorted at. The default when you open the page is an interesting one- "005 MID-ISLAND NY". Almost all New York zip codes start with a 1, but the Mid-Island facility in Melville, which serves codes beginning 117, 118 and 119, also sorts mail addressed to the IRS processing center in Holtsville with the zip code 00501- which happens to be the lowest zip code in current use.