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Add Pacific Time (Canada) and Alberta Time zone mappings

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Adds two friendly zone mappings: Pacific Time (Canada) → America/Vancouver, Alberta → America/Edmonton

Add Pacific Time (Canada) and Alberta Time zone mappings by Saidbek · Pull Request #58321 · rails/rails · GitHub

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Add Pacific Time (Canada) and Alberta Time zone mappings - #58321

#58321

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guilleiguaran merged 2 commits into

rails:mainrails/rails:mainfrom

Saidbek:fix/as-timezone-canada-pacific-mountainSaidbek/rails:fix/as-timezone-canada-pacific-mountainCopy head branch name to clipboard

Aug 12, 2026

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Add Pacific Time (Canada) and Alberta Time zone mappings#58321

guilleiguaran merged 2 commits into

rails:mainrails/rails:mainfrom

Saidbek:fix/as-timezone-canada-pacific-mountainSaidbek/rails:fix/as-timezone-canada-pacific-mountainCopy head branch name to clipboard

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@Saidbek

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@SaidbekSaidbek commented Jul 31, 2026 •

edited by guilleiguaran

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Motivation / Background

Fixes #58316.

British Columbia and Alberta no longer share winter clocks with US Pacific and Mountain time. The existing Pacific Time (US & Canada) and Mountain Time (US & Canada) mappings still resolve to America/Los_Angeles and America/Denver, so apps and users treating those names as a proxy for BC or Alberta will be an hour off every winter.

Detail

This Pull Request adds two friendly zone mappings:

  • Pacific Time (Canada) → America/Vancouver
  • Alberta → America/Edmonton

The existing US & Canada entries are left unchanged for compatibility.

Additional information

Follows the same pattern as other regional divergences (Arizona, Saskatchewan, Atlantic Time (Canada)). Actual DST/offset rules still come from IANA tzdb (BC in 2026a, 2026b, Alberta in 2026c).

Checklist

Before submitting the PR make sure the following are checked:

  • This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
  • Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
  • Tests are added or updated if you fix a bug or add a feature.
  • CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

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All reactions @github-actions github-actions Bot added the activesupport label Jul 31, 2026

@adamhollett

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adamhollett commented Jul 31, 2026

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Thanks for taking this on. This may have been missing from my reporting of the issue but I don’t think mapping Mountain Time to Edmonton is correct. Alberta’s new time zone is being referred to as “Alberta Time” (which covers Edmonton). I don’t believe this name has been recognized or added in to TZInfo yet. It might be more correct to map Mountain Time to America/Yellowknife.

This graphic on Wikipedia is a good way to see the new time zone situation: https://en.wikipedia.org/wiki/Time_in_Canada#/media/File:Canada_time_zone_map_-_en.svg

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@Saidbek

[Add Pacific Time (Canada) and Alberta Time zone mappings](/rails/rails/pull/58321/commits/38c63e2013c44a6b1264a536d90ee2720174e01a "Add Pacific Time (Canada) and Alberta Time zone mappings British Columbia and Alberta no longer share winter clocks with US Pacific and Mountain time. Keep the existing US & Canada entries for compatibility and add Canada-specific friendly names mapped to America/Vancouver and America/Edmonton. Fixes #58316.") …

[38c63e2](/rails/rails/pull/58321/commits/38c63e2013c44a6b1264a536d90ee2720174e01a)

British Columbia and Alberta no longer share winter clocks with US Pacific and Mountain time. Keep the existing US & Canada entries for compatibility and add Canada-specific friendly names mapped to America/Vancouver and America/Edmonton.

Fixes rails#58316.

@Saidbek

Saidbek force-pushed the fix/as-timezone-canada-pacific-mountain branch from 64646f1 to 38c63e2 Compare July 31, 2026 19:15

@Saidbek Saidbek changed the title Add Pacific and Mountain Time (Canada) zone mappings Add Pacific Time (Canada) and Alberta Time zone mappings Jul 31, 2026

@Saidbek

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Saidbek commented Jul 31, 2026 •

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@adamhollett Thanks for the note, and for the map.

Agreed Alberta is no longer ordinary Mountain Time - year-round UTC-6, branded Alberta Time (green band on that map, with Sask).

The IANA target was fine though: tzdb 2026c put permanent -06 under America/Edmonton, and there’s no separate Alberta Time id. America/Yellowknife is just a Link to America/Edmonton in tzdb’s backward file, so it wouldn’t behave differently.

I’ve renamed Mountain Time (Canada) to Alberta Time.

🎉 1 adamhollett reacted with hooray emoji

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@jstanley0

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jstanley0 commented Aug 10, 2026

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It’s odd to see “Alberta Time” surrounded by “Hawaii”, “Mazatlan”, etc. Should it just be “Alberta”?

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@guilleiguaran

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guilleiguaran commented Aug 12, 2026

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@Saidbek, Agree with @jstanley0; other places covered have longer names (“Alaska Standard Time”, “Hawaii Standard Time”) but are abbreviated; let’s do the same for Alberta.

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@Saidbek

[Rename Alberta Time zone mapping to Alberta](/rails/rails/pull/58321/commits/ab9c16236c92ee32d35f02426e61f1e642fcd641 "Rename Alberta Time zone mapping to Alberta Match the short place-name style used by neighboring entries (Hawaii, Alaska, Arizona, Saskatchewan, Mazatlan).") …

[ab9c162](/rails/rails/pull/58321/commits/ab9c16236c92ee32d35f02426e61f1e642fcd641)

Match the short place-name style used by neighboring entries (Hawaii, Alaska, Arizona, Saskatchewan, Mazatlan).

guilleiguaran

guilleiguaran approved these changes Aug 12, 2026

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guilleiguaran merged commit dd980d4 into rails:main Aug 12, 2026

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ActiveSupport::TimeZone mapping no longer accurate

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@Saidbek@adamhollett @jstanley0 @guilleiguaran

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