[tz] [PROPOSED PATCH] Fix 1948-1966 transitions for Los Angeles
eggert at cs.ucla.edu
Sat Aug 20 02:25:14 UTC 2016
These changes came from research I did to check the historical
background behind Assembly Bill 385, which would abolish daylight
saving time in California, and which has passed the CA Senate
Appropriations Committee's suspense file. See: White JB. Bill
letting California end Daylight Saving Time clears key
committee. Sacramento Bee 2016-08-11.
* NEWS, northamerica (CA): For America/Los_Angeles, correct
spring-forward transition times from 02:00 to 02:01 in 1948, from
02:00 to 01:00 in 1950-1966. Correct the fall-back transition
date for early 1949 from 1949-01-01 to 1949-01-16.
NEWS | 7 +++++++
northamerica | 35 ++++++++++++++++++++++++++++++++---
2 files changed, 39 insertions(+), 3 deletions(-)
diff --git a/NEWS b/NEWS
index ba26a49..a8479eb 100644
@@ -7,6 +7,13 @@ Unreleased, experimental changes
New leap second 2016-12-31 23:59:60 UTC as per IERS Bulletin C 52.
(Thanks to Tim Parenti.)
+ Changes affecting past time stamps
+ For America/Los_Angeles, spring-forward transition times have been
+ corrected from 02:00 to 02:01 in 1948, and from 02:00 to 01:00 in
+ 1950-1966. The fall-back transition date for early 1949 has been
+ corrected from 1949-01-01 to 1949-01-16.
Changes affecting code
zic no longer generates binary files containing POSIX TZ-like
diff --git a/northamerica b/northamerica
index 6256f97..c9c2061 100644
@@ -413,11 +413,40 @@ Zone America/Denver -6:59:56 - LMT 1883 Nov 18 12:00:04
# north of the Salmon River, and the towns of Burgdorf and Warren),
# Nevada (except West Wendover), Oregon (except the northern 3/4 of
# Malheur county), and Washington
+# From Paul Eggert (2016-08-19):
+# In 1948 California had an electricity shortage. To save electricity,
+# in early February PG&E changed power frequency from 60 to 59.5 Hz during
+# daylight hours, causing electric clocks to lose six minutes per day.
+# (This did not change legal time, and is not part of the data here.)
+# See: Ross SA. An energy crisis from the past: Northern California in 1948.
+# Working Paper No. 8, Institute of Governmental Studies, UC Berkeley, 1973-11.
+# In another measure to save electricity, DST was instituted from 1948-03-14
+# at 02:01 to 1949-01-16 at 02:00, with the governor having the option to move
+# the fallback transition earlier. See pages 3-4 of:
+# Apparently the governor did not exercise the option.
+# In response:
+# Governor Warren received a torrent of objecting mail, and it is not too much
+# to speculate that the objections to Daylight Saving Time were one important
+# factor in the defeat of the Dewey-Warren Presidential ticket in California.
+# -- Ross, p 25
+# Despite the controversy, in 1949 California voters approved Proposition 12,
+# which established DST from April's last Sunday at 01:00 until September's
+# last Sunday at 02:00. This was amended by 1962's Proposition 6, which changed
+# the fall-back date to October's last Sunday. See:
# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER
-Rule CA 1948 only - Mar 14 2:00 1:00 D
-Rule CA 1949 only - Jan 1 2:00 0 S
-Rule CA 1950 1966 - Apr lastSun 2:00 1:00 D
+Rule CA 1948 only - Mar 14 2:01 1:00 D
+Rule CA 1949 only - Jan 16 2:00 0 S
+Rule CA 1950 1966 - Apr lastSun 1:00 1:00 D
Rule CA 1950 1961 - Sep lastSun 2:00 0 S
Rule CA 1962 1966 - Oct lastSun 2:00 0 S
# Zone NAME GMTOFF RULES FORMAT [UNTIL]
More information about the tz