zip code question

sorabji.com: What do you want?: zip code question
By Rowlfe on Monday, June 13, 2005 - 06:33 pm:

    i'm about to do a huge mailing of postcards to the states... i got a mailing list from adbase.com - they have zip codes, but they go like 90210-1107

    i'm used to only seeing the first sets of numbers, what are the other digits after the hyphen for?

By Kazu on Monday, June 13, 2005 - 06:54 pm:

    They refer to a specific area, such as a city block or
    a group of apartments or an individual high-volume
    receiver of mail, sometimes they numbers match a PO
    Box. They aren't essential, I only ever seethem on bills.
    i never use them when I send mail.

By platypus on Monday, June 13, 2005 - 07:25 pm:

    Ah, the old Zip+4. The post office claims that it makes it easier to get your mail where it's going, but I don't use the zip+4 either.

By TBone on Wednesday, June 15, 2005 - 05:13 pm:

    Supposedly, if you include the plus-four part of the zip code, your mail gets to skip a step in the sorting process and could conceivably get to its destination faster.