Originally posted by stecal
I would bet the farm this wheel has already been invented and that the USPS has the data available in several database formats. Are you planning on entering every zip code in the US along with the city name and state? Can I watch?
Personally I can think of better things to watch than this.

Yes, you can get the data directly from the USPS. You can also contact a company based in LaCrosse, WI called First Logic. They have a third party tool that will take either a dbIII, CSV or a fiixed length file and do the following: Cleanup and verify the addresses, including checking zip codes with cities, adding the plus 4, standardizing business names, do a merge sort of the names and addresses, the list goes on. The product is pretty good, although their gui is slightly flaky. but like Stecal said why reinvent the wheel. Especially since a third party tool will keep updating their product and send you new USPS data.