On 7/21/2026 5:36 PM, Tim Parenti via tz wrote:
I've just pushed a few clerical patches to the repository, all
pertaining to commentary:
0001 moves the NEWS item for Paul's recent patch to Colombia 1992 into
the "Unreleased, experimental changes" section.
0002 adds a URL for the new Alberta statute now that it's on the
books, and uses an archival URL for the old one since it no longer
resolves.
0003 fleshes out commentary around the US' 1974/1975 DST experiment,
clarifying that the initial intent had been to apply DST year-round
for 16 months but the subsequent law created an exemption for much of
the second winter.
Thank you for the clarifications. I have recently been reading about the
1974/1975 experiment ... probably something discussed on the list before
... and found the interim DOT report online. I could not find the final
report, but the executive summary for the final study is available.
https://rosap.ntl.bts.gov/view/dot/10504 1974 Interim Report
https://rosap.ntl.bts.gov/view/dot/92250 1975 Final Report Executive
Summary
In the first report there is a decent history of daylight saving time
and description of the test and how the DOT administered the changes,
including the delayed implementation of DST in Idaho and Oregon (until
Feb 3rd), the shift of all but 12 counties in Kentucky into CST
(effectively letting them stay on -05) and discussions of exemptions in
Indiana and Arizona (starting at page 33 of the PDF available online).
Page 39 (labeled 2-7) notes that Idaho and Michigan passed statewide
exemptions in their easternmost time zones (MST and EST) with an
effective date of "the last Sunday of October (October 27, 1974)."
Shortly before that date arrived Public Law 93-434 passed. Idaho
repealed their law but Michigan's law took effect, leaving them with a
full winter of EST (returning to EDT last Sunday of April instead of
last Sunday of February).
America/Detroit has 1975 listed as the date of Michigan moving to EST,
the full date would be 1974 Oct 27.
I am still researching some of the references within the reports. It is
interesting to note that the Interim report refers to YRDST (year round
daylight saving time) but the final report focuses on 8-4 DST (eight
month 4 month). 30 years later the US moved closer to the 8-4 pattern.
