Geographical boundaries for the continental US tz zones

Oscar van Vlijmen ovv at
Sat Jun 2 17:29:58 UTC 2007

> From: Eric Muller
> Date: Wed, 30 May 2007 22:55:25 -0700
> Subject: Geographical boundaries for the continental US tz zones

> I am trying to figure out the geographical extent of the 19 continental
> US timezones defined by tz. Because my goal is ultimately to create a
> freely available digital map, I would like to get definitions in terms
> existing, freely available digital maps, and the ones at
> seem appropriate. Specifically, I plan to use
> countyp020  (county boundaries 2001), statesp020 (states) and timeznp020
> (time zones) [see below for more details on those maps]. I tried to
> translate the comments in the "northamerica" file in terms of operations
> on the elements of those three maps, but I have a few questions/comments.

The boundaries of the US timezones are precisely defined by the DOT.
One of the problems is that the boundary descriptions are laid down in
cadastral coordinates. These can in some cases only with great difficulty be
translated into latitude/longitude.
More information about the boundaries of USA, Canada and other countries on
my Multizones web page.

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