ZIP code / government addressing data expert here :) * ZCTA = ZIP Code Tabulation Area. ZCTAs are established by the *US Census Bureau not the US Postal Service.* ZCTAs have been established to tabulate population statistics around an area people may identify as a city, because there isn't an incorporated legal city there (for instance). * ZIP Code = Zoning Improvement Plan Code. ZIP Codes are established by the US Post Office to *route mail*, *ZIP Codes do not have a direct spatial component, like a polygon boundary, per se.*
Therefore you can't technically map US ZIP Codes with a polygon. Any maps you see where ZIP Codes are mapped, those boundaries are *derived *from addresses. Technically a USPS ZIP Code map would be a point cloud of address points. If you stand on a vacant parcel with no address it also technically does not have a ZIP Code until the USPS says it does. There are many oddities in ZIP Codes, like holes and enclaves. In the USA, ZIP Codes are established based on imaginary boundaries surrounding post office locations. They are set up to route mail efficiently. * End expertise, begin opinion * Since there are areas in the USA where there are no incorporated cities (that is, ones with a government / mayor), people often identify the place they live based on whatever the city field is on their mail. For OSM, I believe we should only be mapping postal codes by attributing them to addresses. CDP and ZCTA boundaries could arguably be included, as some kind of admin level. Elliott Baltimore Co. GIS. On Thu, Jun 26, 2014 at 3:33 PM, Richard Welty <rwe...@averillpark.net> wrote: > On 6/26/14 3:20 PM, John F. Eldredge wrote: > > Postal code usually means Zip code, or its non-USA equivalent, not city. > this is one of those fussy points in US geocoding. > > the zip code can be mapped to the postal "city", which is what is > in everyone's addresses, and is what i think most us residents > initially expect when typing an address into a search box. > > the underlying point being that there isn't one true geocoder, > it depends entirely on what you're trying to accomplish. something > driven by postal codes/addresses can be correct for many > applications, while being wrong for others. > > to my mind the fact that we keep going in circles about this > is evidence that we're thinking about the problem the wrong way. > > richard > > -- > rwe...@averillpark.net > Averill Park Networking - GIS & IT Consulting > OpenStreetMap - PostgreSQL - Linux > Java - Web Applications - Search > > > > _______________________________________________ > Talk-us mailing list > Talk-us@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-us > > -- Elliott Plack http://about.me/elliottp
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