jtara - 2:56 am on Jan 17, 2008 (gmt 0)

No. Almost nobody uses it on personal mail.

But it appears on almost all business mail.

There are incentives for bulk mailers to use zip+4 - cheaper postage. So, almost all businesses that do any significant mailing must use a database to look-up the zip+4. (Anybody can just go to the U.S. Postal Service web site and look up zip+4s. They just don't do it.)

You aren't going to get consumers to type-in their zip+4 code.

Yes, zip codes can be too broad. I live on the edge of the zipcode for downtown San Diego. If I do a local search on my own zipcode, almost everything that comes up is downtown and inconvenient. So, I've learned to type-in the adjoining zip code that is more accessible to me.

This ^ is an easy solution, and one that local search sites should educate consumers on.

Maybe they could allow users to type-in TWO zip codes, if you are near the edge between two of them.

Zip+4, on the other hand, is VERY specific. I know that my zip+4 is for my 40-unit condo complex. Some zip+4's are for a single floor of an office building, a single company, or a single department in a company.

I imagine Bill Gates has his own zip+4 - or a few. ;)