TZ History Every time zone change, ever made, explained

America/Port_of_Spain

Time zone identifier: America/Port_of_Spain

Current civil offset: -04:00 (AST)

Current DST state: Observing Standard Time

First standard time adoption: Adopted on 1912-03-02

Local Mean Time (LMT): -04:06:04 based on geographic meridian

Total recorded transitions: 1 transitions across 2 distinct offsets

Associated countries: TT

Aliases (Link targets): America/Marigot, America/St_Barthelemy

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Historical Offset Step Chart (1880 to Present)

-6:00 -5:00 -4:00 -3:00 1880 1900 1920 1940 1960 1980 2000 2020

Text summary: America/Port_of_Spain shifted between 2 distinct offsets from 1912-03-02 through the modern era.

Complete Transition History (1 Transitions)

UTC Instant Local Wall Time Shift Abbreviation DST Effect
1912-03-02T04:06:04Z 1912-03-02 00:06:04 -04:06:04 → -04:00 AST No gap

Notes from the Maintainers

Source: backzone (Lines 803 to 828) 
United States

From Paul Eggert (2018-03-18):
America/Palm_Springs would be tricky, as it kept two sets of clocks
in 1946/7.  See the following notes.

From Steve Allen (2018-01-19):
The shadow of Mt. San Jacinto brings darkness very early in the winter
months.  In 1946 the chamber of commerce decided to put the clocks of Palm
Springs forward by an hour in the winter.
https://www.desertsun.com/story/life/2017/12/27/palm-springs-struggle-daylight-savings-time-and-idea-sun-time/984416001/
Desert Sun, Number 18, 1 November 1946
https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19461101
has proposal for meeting on front page and page 21.
Desert Sun, Number 19, 5 November 1946
https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19461105
reports that Sun Time won at the meeting on front page and page 5.
Desert Sun, Number 37, 7 January 1947
https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19470107.2.12
front page reports request to abandon Sun Time and page 7 notes a "class war".
Desert Sun, Number 38, 10 January 1947
https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19470110
front page reports on end.

Trinidad and Tobago

Attributed Statements:

Paul Eggert (2018-03-18):

America/Palm_Springs would be tricky, as it kept two sets of clocks in 1946/7. See the following notes.

Steve Allen (2018-01-19):

The shadow of Mt. San Jacinto brings darkness very early in the winter months. In 1946 the chamber of commerce decided to put the clocks of Palm Springs forward by an hour in the winter. https://www.desertsun.com/story/life/2017/12/27/palm-springs-struggle-daylight-savings-time-and-idea-sun-time/984416001/ Desert Sun, Number 18, 1 November 1946 https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19461101 has proposal for meeting on front page and page 21. Desert Sun, Number 19, 5 November 1946 https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19461105 reports that Sun Time won at the meeting on front page and page 5. Desert Sun, Number 37, 7 January 1947 https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19470107.2.12 front page reports request to abandon Sun Time and page 7 notes a "class war". Desert Sun, Number 38, 10 January 1947 https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=DS19470110 front page reports on end. Trinidad and Tobago

Years on Record

1912

Methodology Note: The 1970 Rule

tzdb guarantees accuracy for timestamps from 1970 onwards. Transitions prior to 1970 represent best-effort historical reconstructions.