FW: "info about the world time zones"

Paul Eggert eggert at twinsun.com
Thu Dec 18 19:31:47 UTC 1997

   From: 	Brian Sawyer[SMTP:bsawyer at mtnia.com]
   Sent: 	Thursday, December 18, 1997 1:42 AM

   I'm wondering if you have any info about the world time zones, not by
   maps but numbers.  example:  Marshalltown, Iowa to Los Angelos  -2 hours
						   to New York   +1 hour
   and so on.

It's not as simple as that, since differences between cities vary with
time.  For example, during the summer Phoenix is two hours behind
Marshalltown, but during the winter, it's only one hour behind.

If you just want a simple listing with major cities, you can use the
tz database at <ftp://elsie.nci.nih.gov/pub/>, using America/Chicago
to represent Marshalltown (this should be valid for dates at least
back to 1970).  For example, here's a shell transcript to illustrate
the current times in Marshalltown and Los Angeles.

	$ TZ=America/Chicago date # current time in Marshalltown:
	Thu Dec 18 13:26:06 CST 1997
	$ TZ=America/Los_Angeles date # current time in Los Angeles:
	Thu Dec 18 11:26:06 PST 1997

If you're building a web site, this sort of thing can be easily done
in a CGI script; see <http://www.bsdi.com/date> for an example of this.

If you want more detailed listings, by far the best tabular source of
historical time zone data that I know of are the following books,
which contain location names and time zone histories for thousands of
locations around the globe.  They will tell you more about
Marshalltown's time zone history than you probably know yourself.

	Thomas G. Shanks, The American Atlas (5th edition),
	San Diego: ACS Publications, Inc. (1991).

	Thomas G. Shanks, The International Atlas (4th edition),
	San Diego: ACS Publications, Inc. (1995).
	[This covers places outside the United States.]

A good source for detailed recent time zone data is the International
Air Transport Association's Standard Schedules Information Manual
(IATA SSIM), published semiannually.  However, this is considerably
more expensive than Shanks, and it covers only airports, whereas
Shanks covers more burgs and hamlets than even my Rand McNally atlas
does, and does an excellent job for most places in the US (though even
he throws up his hands at the time zone history of Indiana).

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