On Fri, 10 Jul 2009 11:07:20 +1000 Ron Savage <[email protected]> wrote:
> Hi Folks > > For a home-use module, I use American postal data from ZipCodeWorld > > http://www.zipcodeworld.com/index.htm I have dealt with this issue on a number of projects over the years. The most recent "open source" version of the data is US Census data from from a few years ago. However, New postal code databases are released *every month* with new updates. It's my sense you need fresh data about every 3 to 6 months to stay very current. It does seem like it should be public data, but it's not now. I have used at least 3 Zipcode vendors over the years. I quit using TPSnet, although I don't recall why now. I'm currently using this vendor: http://www.zip-codes.com/ But they are not perfect, either. In a recent update, I had the geo-spatial data *disappear* in some zipcodes. The explanation was that it was determined that the coordinates needed to be recalculated, but weren't available yet. In that case, I would expect the vendor to do the service of continuing to ship the older slightly less accurate version rather than no coordinates at all. Also note that there is sometimes a lag time between when new zipcodes are published and when the coordinates for the zipcodes are available. This vendor has been been shipping zeros for the coordinates in those cases. Some other vendor (I'm not recalling which one now), "cheats" by using a post office location as the center of zipcode, until the official coordinates are published. I think that's actually the better behavior, because at least people in those zipcodes can search for themselves with *some result* rather than waiting months before the zipcode is useable in geo-spatial searches at all. Because I have learned not to trust Zipcode vendors, we've written our own kind of zipcode update "diffing" tool, so with each update I can get my own report of which zipcodes have been added and removed, as well as which ones have missing geo-spatial data. Right now that tool is specific to our data model storage, so it's not suitable for release. If you are also tracking zipcode updates for a project, I do recommend you QA the published updates like this... In my experience there are nearly always some anolomies that need reviewed and sometimes manually addressed. Mark -- . . . . . . . . . . . . . . . . . . . . . . . . . . . Mark Stosberg Principal Developer [email protected] Summersault, LLC 765-939-9301 ext 202 database driven websites . . . . . http://www.summersault.com/ . . . . . . . . ##### CGI::Application community mailing list ################ ## ## ## To unsubscribe, or change your message delivery options, ## ## visit: http://www.erlbaum.net/mailman/listinfo/cgiapp ## ## ## ## Web archive: http://www.erlbaum.net/pipermail/cgiapp/ ## ## Wiki: http://cgiapp.erlbaum.net/ ## ## ## ################################################################
