[tz] Mexico on track to abolish DST

[Tim Parenti]

On Fri, 28 Oct 2022 at 16:26, Paul Eggert <eggert at cs.ucla.edu> wrote:

> On the other hand it also says that the much larger Ciudad Juárez (which
> will become -06 with US DST rules) will now start to disagree with the
> nearby El Paso (-07 with US DST rules) - that is, starting Sunday the
> two neighboring cities will almost invariably disagree about the time of
> day.


For what it's worth, the draft law circulated in July lists the state of
Chihuahua in the "Zona Pacifico", corresponding to 105°W or UTC-07.
See Chapter 1, Article 3(II):
http://gaceta.diputados.gob.mx/PDF/65/2022/jul/20220706-III.pdf#page=23
So the image from the Energy Secretary on Twitter, putting the entirety of
Chihuahua in "Zona Centro" (UTC-06), is at least a departure from that
draft.
https://twitter.com/rocionahle/status/1585682205417799688
(Chapter 2 of the draft from July puts all of Chihuahua's border area into
UTC-06 during US DST; that is, the status quo.)

There does at least seem to be some amount of general confusion on social
media based on a cursory Twitter search.  So without updated legal text in
front of us, we're not really going to be able to verify this much better,
as there's only so much we can likely glean from sparse news reports.

One possible scenario: The bulk of Chihuahua would move into "Zona Centro"
(UTC-06) by not changing its clocks this weekend, while the existing
arrangement of -07/-06 with US DST could continue along Chihuahua's entire
border region.  This would have the net effect that Juárez would be behind
the rest of Chihuahua in the winter, rather than ahead of it in the summer,
and would maintain year-round compatibility between Ciudad Juárez, El Paso
County, and Hudspeth County, while also maintaining the existing year-round
one-hour difference from places like Ojinaga to Presidio and Brewster
Counties.

Alternatively, supposing -07/-06 is maintained in Juárez and environs,
maybe the eastern portions of Chihuahua's border region might follow the
rest of Chihuahua in advancing their logical zone into "Zona Centro".
Assuming those border areas continue to observe US DST rules, that would
put them on -06/-05, eliminating nearby cross-border time differences east
of some point, but necessitating a line to be drawn somewhere to separate
the two timekeeping regimes.  Assuming an extension of the Texas' time zone
boundary between Hudspeth and Presidio Counties, that would put such a
dividing line near Lomas de Arena in Chihuahua.

All of the above is just speculation on how individual municipalities and
regions might end up aligning their timekeeping if they're operating on the
same (limited) information we have.  Perhaps local officials do know more
about the details, but if so, we haven't yet seen them.

This may be one of those (thankfully rare) cases where, knowing there is
potential for much confusion and that we really can't get anything out
ahead of the changes anyway, it may just be best to "wait and see" what
folks actually begin observing before making descriptive updates to the
data.  Which is a shame, given how long this has been on our radar.

--
Tim Parenti
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