On 2018-03-19 09:18, Glenn A. Walsh wrote in a post to a different mailing list:
Centennial: Official Enactment of U.S. Time Zones & Daylight Saving Time A century ago today (March 19), U.S.President Woodrow Wilson signed into law the Standard Time Act of1918, which officially established time zones in the United States aswell as Daylight Saving Time. Although time zones had beenunofficially observed for a few decades. MORE INFO - CLICK ON IMAGE OR LINK --- LIKE THIS POST? - PLEASE SHARE! Link >>> http://spacewatchtower.blogspot.com/2018/03/centennial-official-enactment-of...
The link describes (among many other things) how the Allegheny Observatory synchronized the switch of US railway times to grid time zones. As one would expect, the switch was done at a single instant, when UT was 1883-11-18 + 18 h. This differs from the current description in tzdb which uses different instants for different target time zones -- not a likely choice for simplifying a nationwide railway schedule. Thus I propose: - Zone America/Los_Angeles -7:52:58 - LMT 1883 Nov 18 12:07:02 + Zone America/Los_Angeles -7:52:58 - LMT 1883 Nov 18 10:07:02 - Zone America/Boise -7:44:49 - LMT 1883 Nov 18 12:15:11 + Zone America/Boise -7:44:49 - LMT 1883 Nov 18 10:15:11 - Zone America/Phoenix -7:28:18 - LMT 1883 Nov 18 11:31:42 + Zone America/Phoenix -7:28:18 - LMT 1883 Nov 18 10:31:42 - Zone America/Denver -6:59:56 - LMT 1883 Nov 18 12:00:04 + Zone America/Denver -6:59:56 - LMT 1883 Nov 18 11:00:04 - Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 + Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 11:12:53 - Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 12:14:21 + Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 11:14:21 - Zone America/North_Dakota/Center -6:45:12 - LMT 1883 Nov 18 12:14:48 + Zone America/North_Dakota/Center -6:45:12 - LMT 1883 Nov 18 11:14:48 - Zone America/New_York -4:56:02 - LMT 1883 Nov 18 12:03:58 + Zone America/New_York -4:56:02 - LMT 1883 Nov 18 13:03:58 Michael Deckers.