Hi Mark On Fri, 2009-07-10 at 11:46 -0400, Mark Stosberg wrote: > 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.
Wow! $many x $thanx for the details. I was not aware of those types of complexities. For my use not much is required, but I'll be more cautious now. -- Ron Savage [email protected] http://savage.net.au/index.html ##### 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/ ## ## ## ################################################################
