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<div class="moz-cite-prefix">On 5/1/15 11:47 AM,
<a class="moz-txt-link-abbreviated" href="mailto:todd.d.robbins@gmail.com">todd.d.robbins@gmail.com</a> wrote:<br>
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<blockquote
cite="mid:CAM9_6uPH0mR55O4y4fw_AmcdPQA93m8TmrQufQ8piXkdR_xwiQ@mail.gmail.com"
type="cite">
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<div dir="ltr">Richard,
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<div>Great point about administrative boundaries and ZIP code
boundaries. It'd be really interesting to see the evolution of
ZIP codes over the decades.</div>
<div><br>
</div>
<div>Has anyone seen visualizations of ZIP changes previously?
Or know whether there are historical datasets of ZIP
boundaries?</div>
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<br>
</blockquote>
the USPS has historically held zip code data closely as it's a
profit center;<br>
they sell it to shippers under fairly restrictive terms of service.<br>
additionally, they maintain it as a set of routes, not as a set of
polygons;<br>
there are reasons why a poly representation of the data can only be<br>
approximate.<br>
<br>
the Census Bureau has their ZCTA data set, which is a polygonal<br>
approximation of zip code data that they use for various statistical<br>
exercises. but it only goes back as far as the TIGER effort goes, so<br>
far as i know. or at least, any pre-TIGER data isn't readily
available.<br>
ZCTA is public domain and available in various formats on the<br>
TIGER download site.<br>
<br>
richard<br>
<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-abbreviated" href="mailto:rwelty@averillpark.net">rwelty@averillpark.net</a>
Averill Park Networking - GIS & IT Consulting
OpenStreetMap - PostgreSQL - Linux
Java - Web Applications - Search</pre>
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