I posted some comments on the blog post about zip codes:<br><br><p>For splitting up OSM data, I suggest splitting data up by counties or other geographic units (e.g. census tracts).</p>
<p>Zip code boundaries are problematic and should not be imported. In
reality, zip codes are merely attributes assigned to addresses and
street segments, and not geographic areas. </p>
<p>People have attempted to create zip code boundaries, though there is
no standard way of creating them. The Census Bureau's zip code
boundaries differ from other sources (e.g. county GIS departments).
Also, zip code "boundaries" change all the time, as new
addresses/buildings are added for mail delivery. </p>
<p>The only official zip code "boundaries" would come from the USPS,
however the USPS does not publish them and has them for internal use
only. Changes in zip code assignments and boundaries are done by a GIS
person at the regional postal facilities (e.g. in Dulles, VA) who
adjusts them in ArcView (or MapInfo), without keeping a history of the
changes.</p>
<p>For more about issues with zip code polygons, see: <a href="http://www.biomedcentral.com/content/pdf/1476-072x-5-58.pdf" rel="nofollow">http://www.biomedcentral.com/content/pdf/1476-072x-5-58.pdf</a></p>
<p>If we end up deciding to import zip codes, it should be done only
after much discussion and with a lot of care. They should be assigned
to address points, and not as boundaries.</p><br>About the data posted to <a href="http://archive.org">archive.org</a>:<br><br><p>For the Census zip code boundaries, there are the 5-Digit ZIP Code Tabulation Area (2002), linked from <a href="http://www2.census.gov/cgi-bin/shapefiles2009/state-files?state=34" rel="nofollow">http://www2.census.gov/cgi-bin/shapefiles2009/state-files?state=34</a>.</p>
<p>There other versions of Census zip code boundaries, aside from that
one. From the <a href="http://archive.org">archive.org</a> link and data link there, I can't tell which
it is.</p><p><br></p><p>And, according to the Census TIGER technical documentation:</p>
<p>"Data users should not use ZCTAs to identify the official USPS ZIP
Code for mail delivery. The U.S. Postal Service (USPS) makes periodic
changes to ZIP Codes to support more efficient mail delivery. As a
result, the original Census 2000 and 2002 ZCTAs may no longer match
current ZIP Codes."</p>
<p><a href="http://www.census.gov/geo/www/tiger/tgrshp2009/TGRSHP09.pdf" rel="nofollow">http://www.census.gov/geo/www/tiger/tgrshp2009/TGRSHP09.pdf</a></p><br>Regards,<br><br>Katie<br>