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 nationalatlas.gov 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. http://home-4.tiscali.nl/~t876506/Multizones.html