As long as we're considering decreasing the historical fidelity of assorted pre-1970 timestamps, I'd like to make a modest suggestion: forget all the "LMT" offsets for years before standardized timezones prevailed, and just assume that the oldest documented standard-time offset in each zone goes back indefinitely far. The reason I suggest this is that we regularly get questions on the Postgres lists from novices who are confused by this behavior (pardon the SQL-isms): postgres=# set timezone = 'UTC'; SET postgres=# select timestamptz '1884-01-01 12:00 America/New_York'; timestamptz ------------------------ 1884-01-01 17:00:00+00 (1 row) This is, of course, saying that noon in New York translates to 1700 UT ... postgres=# select timestamptz '1883-01-01 12:00 America/New_York'; timestamptz ------------------------ 1883-01-01 16:56:02+00 (1 row) ... uh, what? The novices are definitely not expecting that, and they don't find it helpful. We have to explain it away as "that's what tzdb says", but it's still unhelpful. It's even sillier when you consider postgres=# select timestamptz '1752-09-10 12:00 America/New_York'; timestamptz ------------------------ 1752-09-10 16:56:02+00 (1 row) as calendar experts will recall that no such date was recognized in the British colonies. So although it's debatable whether we even know what day it is, for sure we know the UTC offset to the second. So basically, if we're willing to use proleptic Gregorian calendar for years before anyone was actually using that calendar, it's not very clear why we shouldn't use proleptic standard time too. I'd be willing to consider implementing that behavior in Postgres if I could tell (a) that a given offset is LMT not standardized time and (b) what the zone's oldest standardized offset is. But AFAICT that's not possible without mucking with the behavior of localtime.c, which I'd much prefer not to. So ... how about just dropping this oddity from the source data? regards, tom lane