[Talk-us] what do we mean by geocoding?

[Steven Johnson]

On Sun, Jun 23, 2013 at 1:12 PM, Bryce Nesbitt <bryce2 at obviously.com> wrote:

>
> At SOTM-US (State of the Map US) I spoke to Steven Johnson of the Census
> Bureau on the issue of what data USPS actually has internally (as the
> Census Bureau has some special licensed access to this data).
>
> Yes, just to amplify: the Census Bureau purchases the Delivery Sequence
File (DSF) from USPS on an ongoing basis (at least 2x/year). The use of the
DSF dates from 1994 and Congressional authorization was required for the
Bureau to use the DSF. The DSF served as the foundation for the Bureau's
Master Address File (MAF). The DSF is by far the largest source of address
data for the Bureau, in excess of 90%.

Apparently, the USPS does not even know the geocoordinates of most of their
> assets (e.g. post boxes, post offices, delivery addresses).  They do have a
> near perfect database of *what* these assets are, just not
> the coordinates.  And that itself is useful.  Knowing a postbox exists is a
> huge clue to geocoding it.  Knowing a postbox has been removed from service
> is a huge clue.
>

Actually, I think I was referring to ZIP codes (but you're forgiven for not
recalling the details. ;-) ). The USPS *does not* maintain ZIP codes as
polygon features, because the ZIP code is associated with a delivery
*point* (i.e. a postal address). The Census Bureau combines those into
something known as "ZIP Code Tabulation Areas", which are an approximation
created by drawing boundaries around a collection of *points* that have ZIP
code in common. Many other commercial vendors create something similar. But
there is no official database of ZIP code polygons.

As to whether USPS has coordinates/geocoded coords for all of the postal
'furniture' out there, that I don't know.

-- SEJ
-- twitter: @geomantic
-- skype: sejohnson8

There are two types of people in the world. Those that can extrapolate from
incomplete data.
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