On Fri, 20 Feb 2026 at 15:07, Brooks Harris via tz <tz@iana.org> wrote:
As Paul Eggert pointed out on the list: Re: [tz] Tzdb and the Sunshine Protection Act, 2023-03-02 … My biggest worry is the set of backward compatibility zones EST5EDT, CST6CDT, MST7MDT, PST8PDT as their continued use would lead to so much confusion that they'd be more trouble than they're worth.
That certainly would remain a general concern for this project and the software ecosystem. But "half-daylight time" would additionally break a lot of viable workarounds for other devices: In particular, radio-controlled clocks sold in the continental US which obtain UTC-timestamped signals from WWVB are generally configurable to a narrow range of integer offsets from UTC, and DST observance can usually be disabled on most such devices. Some may include −4 for AST which would help residents in a permanent EDT situation, but in general no available setting would accommodate "half-daylight zones" like −4½, −5½, etc. On Fri, 20 Feb 2026 at 22:09, David Braverman via tz <tz@iana.org> wrote:
One thing I don't see in any of these proposals: simply _adjusting the boundaries._ In the US, and I would expect in Canada also, states and provinces are free to divide themselves between time zones.
Unlike in Canada, where timezones are strictly a provincial or territorial matter, US states are NOT actually free to self-select their timezones. Either the US Department of Transportation can change boundaries (in response to proposals from state/local governments) or Congress can legislate new boundaries. (States' only real say in the matter relates to opting out of DST observance, and even that is a bit specific in how exactly it can be done.) Since "permanent standard time" is equivalent to "permanent daylight time in the next zone westward", I do suspect that such shifts could likely gain more public acceptance if accompanied by thoughtful boundary adjustments, though bringing dividing lines through new areas brings about its own issues. -- Tim Parenti