[Talk-us] Fwd: Postal Code Extract

[Paul Johnson]

The Post Office *definitely* doesn't do that.  Post office ZIP codes are
defined by route, not area, and have significant outliers, particularly in
areas served by multiple post offices and extremely rural areas.  You might
see three different zips and at least 3 zip+4's on a single block with USPS
ZIPs.  If you're trying to get areas, use Census ZIPs.  They're nearly
identical but I'm fairly certain the Census ZIPs are more consistently
contiguous regions.


On Fri, Aug 30, 2013 at 5:12 PM, John F. Eldredge <john at jfeldredge.com>wrote:

> You may want to double-check with the Post Office, to find out whether
> there is the possibility that there may legitimately be outliers in some
> cases. I don't think the US Post Office guarantees that zip codes will
> always define a single polygon with no outliers.
>
>
> Clifford Snow <clifford at snowandsnow.us> wrote:
>>
>>
>> On Fri, Aug 30, 2013 at 2:13 PM, Eric Fischer <enf at pobox.com> wrote:
>>
>>> Or if you just want the US zip code polygons and don't care if you get
>>> them from OSM or somewhere else, you could just download the shapefile of
>>> Census Zip Code Tabulation Areas from
>>> http://www2.census.gov/geo/tiger/TIGER2013/ZCTA5/
>>>
>>
>>
>> It's the OSM data I'm after. I'd like to do a test to make sure that
>> there are no outliers. I would expect that I should be able to construct a
>> polygon from zip codes. If not, then there it might mean an import problem.
>> I'm going to try Mike's suggestion of increasing the timeout. I did
>> increase it, but not as much as suggested.
>>
>>
>> --
>> Clifford
>>
>> OpenStreetMap: Maps with a human touch
>>
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> --
> John F. Eldredge -- john at jfeldredge.com
> "Darkness cannot drive out darkness:
> only light can do that. Hate cannot drive out hate: only love can do
> that." -- Dr. Martin Luther King, Jr.
>
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