DST in Baja California 1973
TZ maintains for zone America/Tijuana that there was not DST observed between 1961 and 1975.
# Baja California Zone America/Tijuana -7:48:04 - LMT 1922 Jan 1 7:00u -7:00 - MST 1924 -8:00 - PST 1927 Jun 10 -7:00 - MST 1930 Nov 15 -8:00 - PST 1931 Apr 1 -8:00 1:00 PDT 1931 Sep 30 -8:00 - PST 1942 Apr 24 -8:00 1:00 PWT 1945 Aug 14 23:00u -8:00 1:00 PPT 1945 Nov 15 # Peace -8:00 - PST 1948 Apr 5 -8:00 1:00 PDT 1949 Jan 14 -8:00 - PST 1950 May 1 -8:00 1:00 PDT 1950 Sep 24 -8:00 - PST 1951 Apr 29 2:00 -8:00 1:00 PDT 1951 Sep 30 2:00 -8:00 - PST 1952 Apr 27 2:00 -8:00 1:00 PDT 1952 Sep 28 2:00 -8:00 - PST 1954 -8:00 CA P%sT 1961 -8:00 - PST 1976 -8:00 US P%sT 1996 -8:00 Mexico P%sT 2001 -8:00 US P%sT 2002 Feb 20 -8:00 Mexico P%sT 2010 -8:00 US P%sT
A user of our astrology service, born in 1973 in he border town Mexicali claimed that they observed DST in his town, just like on the other side of the border in California, when he was born on 30 May 1973. I did a quick newspaper archive research on https://hndm.iib.unam.mx/ and found that Título: Periódico Oficial del Estado de Baja California Norte Fecha: 1973-04-20 states clearly that DST was observed from last Sunday in April to last Sunday in October. This means the the TZ table above is false, at least for 1973. I assume that the same is the case for several other years. I attach the screenshot for 1973 The page https://hndm.iib.unam.mx/consulta/publicacion/visualizar/558075be7d1e63c9fea... should allow to search for other years as well. I used the keywords *hora legal* for my search, though do not see that now in the URL.
I have a few more data from the official bulletin for DST begin or end in Baja California 1964 1967 1969 1972 1973 (already sent) 1974 1975 1976 I do not know whether it is safe to assume that it also applied in the years where I did not yet find proof. The 1974 end of DST contains a reference to an Acuerdo of 1973-dec-20 which I could not find. It was the winter of the 'oil crisis' if I remember correctly. The US started DST already on 6-jan-1974. One might assume that Baja California, which followed US-CA in all these other yours, did the same. On 29.07.2025 13:59, Alois Treindl via tz wrote:
TZ maintains for zone America/Tijuana that there was not DST observed between 1961 and 1975.
# Baja California Zone America/Tijuana -7:48:04 - LMT 1922 Jan 1 7:00u -7:00 - MST 1924 -8:00 - PST 1927 Jun 10 -7:00 - MST 1930 Nov 15 -8:00 - PST 1931 Apr 1 -8:00 1:00 PDT 1931 Sep 30 -8:00 - PST 1942 Apr 24 -8:00 1:00 PWT 1945 Aug 14 23:00u -8:00 1:00 PPT 1945 Nov 15 # Peace -8:00 - PST 1948 Apr 5 -8:00 1:00 PDT 1949 Jan 14 -8:00 - PST 1950 May 1 -8:00 1:00 PDT 1950 Sep 24 -8:00 - PST 1951 Apr 29 2:00 -8:00 1:00 PDT 1951 Sep 30 2:00 -8:00 - PST 1952 Apr 27 2:00 -8:00 1:00 PDT 1952 Sep 28 2:00 -8:00 - PST 1954 -8:00 CA P%sT 1961 -8:00 - PST 1976 -8:00 US P%sT 1996 -8:00 Mexico P%sT 2001 -8:00 US P%sT 2002 Feb 20 -8:00 Mexico P%sT 2010 -8:00 US P%sT
A user of our astrology service, born in 1973 in he border town Mexicali claimed that they observed DST in his town, just like on the other side of the border in California, when he was born on 30 May 1973.
I did a quick newspaper archive research on https://hndm.iib.unam.mx/ and found that
Título: Periódico Oficial del Estado de Baja California Norte Fecha: 1973-04-20
states clearly that DST was observed from last Sunday in April to last Sunday in October.
This means the the TZ table above is false, at least for 1973. I assume that the same is the case for several other years.
I attach the screenshot for 1973
The page https://hndm.iib.unam.mx/consulta/publicacion/visualizar/558075be7d1e63c9fea... should allow to search for other years as well.
I used the keywords *hora legal* for my search, though do not see that now in the URL.
Dear Alois and team, thank you so much for the quick followup. I tried doing a quick search for newspapers of the era, but it is proving to be difficult. This website gave me hope for a moment, but so far no luck finding a newspaper that would talk about the time change (would need to be one from the last Sunday of April or October, to be relevant). https://latinonewspapers.uh.edu/s/eng/publicationlist?page=7&sort=dcterms:sp... Of course Mexicali, being the capital city of the Baja California state, has a vast newspaper archive, but unfortunately they don’t have an online presence and an in-person visit is out of the question as I’ve lived in Germany for years now. So sadly, all I can contribute right now is circumstantial evidence: I know that from the time I was born until I left Mexicali (ca. 2000) we always used DST because to have a different time than our neighboring city of Calexico would have been laughable. Calexico was an integral part of our culture and society; for example, everyone would cross the border to go shopping on the weekends or, if the gas was cheaper in the US side that week, everyone would just cross the border to quickly fill the tank and come back (these were simpler, pre-9/11 times). A different time zone would have been quite disruptive and I know for a fact that this was never the case while I lived there (1973-2000). But of course, I have no way to prove this except my word. The hospital I was born in was in fact located two blocks away from the border, and if I set my birth data to show Calexico instead of Mexicali, I do get the correct chart and time. Anyway, if I ever come back to my hometown I will try to find an old newspaper, until then, thank you so much for your help and the attention to this matter. All the best, - Beto Ruiz Alonso betoruizalonso.com <http://www.betoruizalonso.com/>instagram.com/betoruizalonso <http://www.instagram.com/betoruizalonso>
On 29. Jul 2025, at 15:26, Alois Treindl <alois@astro.ch> wrote:
I have a few more data from the official bulletin for DST begin or end in Baja California 1964 1967 1969 1972
1973 (already sent)
1974 1975 1976
I do not know whether it is safe to assume that it also applied in the years where I did not yet find proof.
The 1974 end of DST contains a reference to an Acuerdo of 1973-dec-20 which I could not find. It was the winter of the 'oil crisis' if I remember correctly. The US started DST already on 6-jan-1974.
One might assume that Baja California, which followed US-CA in all these other yours, did the same.
On 29.07.2025 13:59, Alois Treindl via tz wrote:
TZ maintains for zone America/Tijuana that there was not DST observed between 1961 and 1975.
# Baja California Zone America/Tijuana -7:48:04 - LMT 1922 Jan 1 7:00u -7:00 - MST 1924 -8:00 - PST 1927 Jun 10 -7:00 - MST 1930 Nov 15 -8:00 - PST 1931 Apr 1 -8:00 1:00 PDT 1931 Sep 30 -8:00 - PST 1942 Apr 24 -8:00 1:00 PWT 1945 Aug 14 23:00u -8:00 1:00 PPT 1945 Nov 15 # Peace -8:00 - PST 1948 Apr 5 -8:00 1:00 PDT 1949 Jan 14 -8:00 - PST 1950 May 1 -8:00 1:00 PDT 1950 Sep 24 -8:00 - PST 1951 Apr 29 2:00 -8:00 1:00 PDT 1951 Sep 30 2:00 -8:00 - PST 1952 Apr 27 2:00 -8:00 1:00 PDT 1952 Sep 28 2:00 -8:00 - PST 1954 -8:00 CA P%sT 1961 -8:00 - PST 1976 -8:00 US P%sT 1996 -8:00 Mexico P%sT 2001 -8:00 US P%sT 2002 Feb 20 -8:00 Mexico P%sT 2010 -8:00 US P%sT A user of our astrology service, born in 1973 in he border town Mexicali claimed that they observed DST in his town, just like on the other side of the border in California, when he was born on 30 May 1973.
I did a quick newspaper archive research on https://hndm.iib.unam.mx/ and found that
Título: Periódico Oficial del Estado de Baja California Norte Fecha: 1973-04-20 <>states clearly that DST was observed from last Sunday in April to last Sunday in October.
This means the the TZ table above is false, at least for 1973. I assume that the same is the case for several other years.
I attach the screenshot for 1973
The page https://hndm.iib.unam.mx/consulta/publicacion/visualizar/558075be7d1e63c9fea... should allow to search for other years as well.
I used the keywords hora legal for my search, though do not see that now in the URL.
<>
<1964_begin_dst_baja_california.png><1967_begin_dst_baja_california.png><1969_end_dst_baja_california.png><1970_end_dst_baja_california.png><1976_begin_dst_baja_california.png><1975_end_dst_baja_california.png><1974_end_dst_baja_california.png><1972_begin_dst_baja_california.png><1973_begin_dst_baja_california.png>
Thanks for that research on Baja California. I installed the attached proposed patches. The first one is for Baja California and goes back to what Shanks said about Tijuana, as this agrees with your data. The second one is commentary about Zapotec timekeeping which I found while looking into the matter.
Good morning, everyone! Allow me to report a bug (see screenshot):  Wanted to try making a new chart now that there’s a patch installed, but now I can’t choose any Mexican city. - Beto Ruiz Alonso betoruizalonso.com <http://www.betoruizalonso.com/>instagram.com/betoruizalonso <http://www.instagram.com/betoruizalonso>
On 4. Aug 2025, at 18:28, Paul Eggert <eggert@cs.ucla.edu> wrote:
Thanks for that research on Baja California. I installed the attached proposed patches. The first one is for Baja California and goes back to what Shanks said about Tijuana, as this agrees with your data. The second one is commentary about Zapotec timekeeping which I found while looking into the matter.<0001-Fix-Baja-California-1951-1961-1975.patch><0002-Add-Schapiro-notes-on-Zapotec-timekeeping.patch>
Refreshing the page fixes it, but I was able to recreate it again (navigate with tab key to “Country” then start to type “Mexico” to land in the Mexico option, then “birth town” automatically defaults to a drop-down menu of these two Macau cities. - Beto Ruiz Alonso betoruizalonso.com <http://www.betoruizalonso.com/>instagram.com/betoruizalonso <http://www.instagram.com/betoruizalonso>
On 5. Aug 2025, at 10:08, Al <albertoruizalonso@gmail.com> wrote:
Good morning, everyone! Allow me to report a bug (see screenshot):
<PastedGraphic-1.tiff>
Wanted to try making a new chart now that there’s a patch installed, but now I can’t choose any Mexican city.
- Beto Ruiz Alonso betoruizalonso.com <http://www.betoruizalonso.com/>instagram.com/betoruizalonso <http://www.instagram.com/betoruizalonso>
On 4. Aug 2025, at 18:28, Paul Eggert <eggert@cs.ucla.edu> wrote:
Thanks for that research on Baja California. I installed the attached proposed patches. The first one is for Baja California and goes back to what Shanks said about Tijuana, as this agrees with your data. The second one is commentary about Zapotec timekeeping which I found while looking into the matter.<0001-Fix-Baja-California-1951-1961-1975.patch><0002-Add-Schapiro-notes-on-Zapotec-timekeeping.patch>
Please report your issue to the vendor of the software you are using! That software should be able to handle whatever you select. How it operates has little to do with time zone data from this project. Does the software you are using support updating from tzdata, do you know the proper process for applying such an update, or has the vendor provided such an update recently? The tzdata package contains the following zones for Mexico: $ grep MX zone.tab zone.tab:MX +1924-09909 America/Mexico_City Central Mexico zone.tab:MX +2105-08646 America/Cancun Quintana Roo zone.tab:MX +2058-08937 America/Merida Campeche, Yucatan zone.tab:MX +2540-10019 America/Monterrey Durango; Coahuila, Nuevo Leon, Tamaulipas (most areas) zone.tab:MX +2550-09730 America/Matamoros Coahuila, Nuevo Leon, Tamaulipas (US border) zone.tab:MX +2838-10605 America/Chihuahua Chihuahua (most areas) zone.tab:MX +3144-10629 America/Ciudad_Juarez Chihuahua (US border - west) zone.tab:MX +2934-10425 America/Ojinaga Chihuahua (US border - east) zone.tab:MX +2313-10625 America/Mazatlan Baja California Sur, Nayarit (most areas), Sinaloa zone.tab:MX +2048-10515 America/Bahia_Banderas Bahia de Banderas zone.tab:MX +2904-11058 America/Hermosillo Sonora zone.tab:MX +3232-11701 America/Tijuana Baja California showing the lat/long ranges are +19°24'..32°32' -086°46'..-117°01'; $ grep Macau zone.tab MO +221150+1133230 Asia/Macau so it looks like that software is mismatching the country selection somehow. The tzcode package utility tzselect provides the selection of zones below for the extreme lat/long coordinates and the country selection, nothing like Macau: $ tzselect Please identify a location so that time zone rules can be set correctly. Please select a continent, ocean, "coord", "TZ", "time", or "now". ... 11) coord - I want to use geographical coordinates. 12) TZ - I want to specify the timezone using a proleptic TZ string. 13) time - I know local time already. 14) now - Like "time", but configure only for timestamps from now on. #? 11 Please enter coordinates in ISO 6709 notation. For example, +4042-07403 stands for 40 degrees 42 minutes north, 74 degrees 3 minutes west. +1924-08646 Please select one of the following timezones, listed roughly in increasing order of distance from +1924-08646. 1) Quintana Roo 4) Campeche, Yucatán 7) Guatemala 10) Central - IN (Perry) 2) Belize 5) Nicaragua 8) Cuba 3) Honduras 6) El Salvador 9) Costa Rica #? $ tzselect Please identify a location so that time zone rules can be set correctly. Please select a continent, ocean, "coord", "TZ", "time", or "now". ... 11) coord - I want to use geographical coordinates. 12) TZ - I want to specify the timezone using a proleptic TZ string. 13) time - I know local time already. 14) now - Like "time", but configure only for timestamps from now on. #? 11 Please enter coordinates in ISO 6709 notation. For example, +4042-07403 stands for 40 degrees 42 minutes north, 74 degrees 3 minutes west. +3232-11701 Please select one of the following timezones, listed roughly in increasing order of distance from +3232-11701. 1) Baja California 5) Mountain - ID (south), OR (east) 9) Mountain (most areas) 2) Pacific 6) Chihuahua (US border - west) 10) Chihuahua (US border - east) 3) MST - AZ (most areas), Creston BC 7) Chihuahua (most areas) 4) Sonora 8) Pacific - BC (most areas) #? $ tzselect Please identify a location so that time zone rules can be set correctly. Please select a continent, ocean, "coord", "TZ", "time", or "now". 1) Africa 2) Americas 3) Antarctica 4) Arctic Ocean 5) Asia 6) Atlantic Ocean 7) Australia 8) Europe 9) Indian Ocean 10) Pacific Ocean ... #? 2 Please select a country whose clocks agree with yours. 1) Anguilla 15) Costa Rica 29) Honduras 43) St Martin (French) 2) Antigua & Barbuda 16) Cuba 30) Jamaica 44) St Pierre & Miquelon 3) Argentina 17) Curaçao 31) Martinique 45) St Vincent 4) Aruba 18) Dominica 32) Mexico 46) Suriname 5) Bahamas 19) Dominican Republic 33) Montserrat 47) Trinidad & Tobago 6) Barbados 20) Ecuador 34) Nicaragua 48) Turks & Caicos Is 7) Belize 21) El Salvador 35) Panama 49) United States 8) Bolivia 22) French Guiana 36) Paraguay 50) Uruguay 9) Brazil 23) Greenland 37) Peru 51) Venezuela 10) Canada 24) Grenada 38) Puerto Rico 52) Virgin Islands (UK) 11) Caribbean NL 25) Guadeloupe 39) St Barthelemy 53) Virgin Islands (US) 12) Cayman Islands 26) Guatemala 40) St Kitts & Nevis 13) Chile 27) Guyana 41) St Lucia 14) Colombia 28) Haiti 42) St Maarten (Dutch) #? 32 Please select one of the following timezones. 1) Central Mexico 7) Chihuahua (US border - west) 2) Quintana Roo 8) Chihuahua (US border - east) 3) Campeche, Yucatán 9) Baja California Sur, Nayarit (most areas), Sinaloa 4) Durango; Coahuila, Nuevo León, Tamaulipas (most areas) 10) Bahía de Banderas 5) Coahuila, Nuevo León, Tamaulipas (US border) 11) Sonora 6) Chihuahua (most areas) 12) Baja Californ?ia #? showing all the zones with MX country code, as in the list at the top. On 2025-08-05 02:11, Al via tz wrote:
Refreshing the page fixes it, but I was able to recreate it again (navigate with tab key to “Country” then start to type “Mexico” to land in the Mexico option, then “birth town” automatically defaults to a drop-down menu of these two Macau cities.
That software may only be looking at the first letter in Country: try typing slower to allow it to catch up! It should also prompt for "closest town to birth town", as many towns are not included in most software, and it depends on the gazeteer used: comprehensive global gazeteers are freely available but large: https://download.geonames.org/export/dump/ allcountries.zip 395MB
On 5. Aug 2025, at 10:08, Al <albertoruizalonso@gmail.com> wrote: Good morning, everyone! Allow me to report a bug (see screenshot): Wanted to try making a new chart now that there’s a patch installed, but now I can’t choose any Mexican city. Beto Ruiz Alonso betoruizalonso.com
On 4. Aug 2025, at 18:28, Paul Eggert wrote: Thanks for that research on Baja California. I installed the attached proposed patches. The first one is for Baja California and goes back to what Shanks said about Tijuana, as this agrees with your data. The second one is commentary about Zapotec timekeeping which I found while looking into the matter. <0001-Fix-Baja-California-1951-1961-1975.patch> <0002-Add-Schapiro-notes-on-Zapotec-timekeeping.patch> -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retrancher but when there is no more to cut -- Antoine de Saint-Exupéry
Have my recent (29 July 2025) corrections for zone America/Tijuana between 1961 and 1976 been noticed by the TZ maintainers? I have posted several screenshots from official sources, though so far I have been unable to document every year which I am putting in question.
participants (4)
-
Al -
Alois Treindl -
Brian Inglis -
Paul Eggert