On Fri, 20 Feb 2026 at 15:07, Brooks Harris via tz <[email protected]> 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 <[email protected]> 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
