US presidential election year politics help cause time zone bugs

Paul Eggert eggert at
Mon Oct 26 22:47:57 UTC 1992

Several people on the west coast of the US reported that their Unix
systems failed to switch from daylight savings time to standard time
yesterday, 26 October 1992.  The reason?  When they originally
configured their systems, they were asked to choose one of the
following time zone rules:

	US/Alaska	US/Central	US/Hawaii	US/Pacific
	US/Aleutian	US/East-Indiana	US/Michigan	US/Pacific-New
	US/Arizona	US/Eastern	US/Mountain	US/Samoa

Some people chose `US/Pacific-New' instead of `US/Pacific'.
After all, who wants the old version when you can have the new version?

Unfortunately, `US/Pacific-New' stands for ``Pacific Presidential
Election Time'', which was passed by the House in April 1989 but never
signed into law.  In presidential election years, this rule would have
delayed the PDT-to-PST switchover until after the election, to lessen
the effect of broadcast news election projections on last-minute
west-coast voters.  Thus, US/Pacific-New and US/Pacific have always
been identical -- until yesterday.

This problem comes from combining Arthur David Olson's deservedly
popular time zone software (which you can FTP from in
pub/tz92b.tar.Z) with some overly terse vendor-supplied installation
procedures.  No doubt Olson did not use a more informative name like
`US/Pacific-Presidential-Election' because of the 14-character file
name length limit in many Unix file systems.  In view of yesterday's
experience, though, it seems unwise to make the hypothetical choice
available under any name, since it gives free rein to Murphy's Law.

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