[mikeash]

I just downloaded the standard ones from: https://www.iana.org/time-zones

It appears to have this stuff down to the second. For example:

    # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
    Zone America/New_York	-4:56:02 -	LMT	1883 Nov 18 12:03:58

    # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
    Zone America/Chicago	-5:50:36 -	LMT	1883 Nov 18 12:09:24

Although this won't really be accurate, because it doesn't have every single city. The New_York zone covers the whole eastern time zone even though all the cities in that zone would have been different before 1883. But it is in the database, even if it's not quite right for anything outside of the named cities.

[Dylan16807]

Well that's a mess. Wrong data is worse than missing data for something like this...