At 06:54 9/12/2011, Alois Treindl wrote:
I have researched in newspaper archives, and found an article in the paper 'The Mountain Democrat Times' of 1968 March 28, which confirms that the whole area on the Yuma AZ side of the Colorado River but belonging to California followed even then Arizona time, i.e. MST without observing DST.
It mentions the post office in Bard, CA as an example, and probably it includes the populated places Winterhaven, Ross Corner and Bard.
Before 1968 I found no source. But probably we can assume that this habit has been permanent. The simplest is to include this area with Arizona, for timezone purposes.
Alois et al.: I don't presume to advise this community on how or whether such unofficial exceptions to time zone observance should be handled within the TZ database, but I will pass on my perspective on the phenomena - and hope it sheds some light. In the interest of full disclosure let me be clear that my limited knowledge on the topic is confined to North American nations and is not authoritative. Within that small set of nations the US seems to be the only one with multiple time zone borders clearly and explicitly defined by an acknowledged central authority (the US Dept. of Transportation). So within the US, local unofficial exceptions take on a somewhat different context than in some other nations where such central control may not be as clearly established, or may not be acknowledged by all populations or political subdivisions within the borders of that nation. I am aware of 8 such exceptions in the US. Within each, the scope of the exception can differ. To begin with, the actual borders of each such area are rarely specified with any clarity or authority. Winterhaven CA is a bit of an exception as the "All American Canal" seems to be locally acknowledged as the border, a convenient fixed mapping feature. Within each exception area one can presume that most businesses and residents set their clocks based on the exception, and that metaphorically (and literally, if it exists) the clock in town square displays the exception time. But in each area of exception, official time may still have a foothold in at least some of these contexts: The offices and services of City, County, State and/or Federal government (e.g. the Post Office). Law enforcement and judicial services provided by these various political subdivisions Bars/Liquor stores (depending on state law) Polling places Cell phones and other mobile consumer electronics that automatically adjust local time display For instance, apparently the automated California state law enforcement systems cannot handle multiple time zones. That would make sense as the entire state officially lies within the Pacific time zone. Thus all law enforcement services in Winterhaven follow California time, not Arizona time. And if you are in Pierre SD (which is in the Central time zone) and find you have run out of schnapps a little after midnight (when off-premise liquor sales are shut down by state law), you can venture over the bridge into Fort Pierre - a city and surrounding area that unofficially observes Central time despite being in the Mountain time zone - and find that the clock in the liquor store is set to Mountain time, an hour earlier than the rest of the town. Your party can continue. I find no consistent rule of thumb to use to estimate the scope of time zone exception observance within each area in question. Key factors seem to be whether the area contains an actual municipality (as in Ft. Pierre SD and Phenix City AL), and the degree to which the area is governed by a tribal authority. Other factors are state law, law enforcement systems, and simple custom. In other nations such as Canada and Mexico the scope of exceptions can be even more variable, as there may be less authority or specificity from a central source. Within OnTimeZone.com I treat all exceptions in Mexico and Canada as official due a general lack of clarity or assertion of authority from official sources. Most exceptions in Canada and Mexico have to do with Daylight Saving time observance rather than actual time zone borders. I hope some of this is of use. Regards, Steve Jones OnTimeZone.com