The Politics of Time Zones

Updated Again (see Bill’s comments below): Sri Lanka is finally officially switching to the GMT+5.30 time zone (same as in India) after a decade of confusing back and forth changes to daylight saving time (GMT+6.30), Sri Lanka Time (GMT+6 because GMT+5.30 is India’s time zone). Apparently, the rebels never agreed to the time zone switch of 1996 and have always been in GMT+5.30. Sri Lanka is not the only place with time zone politics.  

Daylight Saving Time in the US has always been confusing with some states like Arizona and parts of some states like Indiana refusing to observe daylight saving time. As if that is not enough President Bush has signed a new law that includes a highly controversial extension of Daylight Saving time which takes effect in 2007. Given the controversy surrounding this, I was not sure if this provision made it into the final bill. After some searching I found the entire text of the law at the Department of Interiors Site [Caution 3MB PDF file]. The relevant provision extracted below:


(a) AMENDMENT.—Section 3(a) of the Uniform Time Act of 1966

(15 U.S.C. 260a(a)) is amended—

(1) by striking ‘‘first Sunday of April’’ and inserting ‘‘second Sunday of March’’; and

(2) by striking ‘‘last Sunday of October’’ and inserting ‘‘first Sunday of November’’.

(b) EFFECTIVE DATE.—Subsection (a) shall take effect 1 year after the date of enactment of this Act or March 1, 2007, whichever is later.

(c) REPORT TO CONGRESS.—Not later than 9 months after the effective date stated in subsection (b), the Secretary shall report to Congress on the impact of this section on energy consumption in the United States.

(d) RIGHT TO REVERT.—Congress retains the right to revert the Daylight Saving Time back to the 2005 time schedules once the Department study is complete.

If you read it carefully, The effective date is March 1, 2007 because the law was enacted on Aug 8, 2005. Interestingly, provision d allows the US to revert the time back to 2005 schedules! Now why couldn’t they simulate the savings using some modeling tools and then decide one way or the other instead of putting everyone in major league turmoil? All this confusion could help IT consulting companies make a lot of money helping companies switch all the software systems back and forth to accomodate this.

Meanwhile, if this site is to be believed, parts of Indiana are switching to Central Time Zone and some other parts are switching to Eastern Time Zone.

Update: Vinnie adds some interesting facts about time zones across the world.

Next time you call someone anywhere in the world, check the time zone one more time, politicians may have switched day for night in the time zone you are calling! 


  1. Anonymous said April 17, 2006, 10:41 pm:

    It’s about time we clarified a few more issues about time.

    Even when we think that we have made a definitive pronouncement on the topic, if we drill down, there is always just one more exception or piece of trivia to be found.

    I have two observations to add to this timely topic:

    1. There is, although not many know it, some confussion over terminology. Most people probably refer to the summer time time shift as Daylight Savings Time. That is officially incorrect. The proper term is Daylight Saving (no “s”) Time. “Saving” is an adjective that modifies “daylight.” Nevertheless, popular usage has a way of imposing itself. Using Google as a linguistic meter, one gets 9,760,000 hits on “daylight saving time” and 6,580,000 on “daylight savings time.” The later is also now referenced in some dictionaries.

    2. One of the states that everyone thinks does not go on to Daylight Saving Time (DST) is Arizona. Just take a look at your time zone setting in the Microsoft Windows clock. No DST change according to it. I am an Arizonan, and I have made the propagation of the news that this is not true my cause celebre since most Arizonans are living under that misconception. The truth is that most of Arizona does not go on DST, but the northcentral and northeastern portion of the state, which is made up of the Navajo Native American Indian reservation, or the Dine Nation as they prefer to call it, does go on DST. While most of the Dine Nation is in Arizona, portions flow over into Utah and New Mexico. These portions of the Dine Nation shift to DST, so the whole tribal area does. It is the largest and most populous reservation in the USA, so I guess it is big enough to get away with it. I have frequently asked if this is just a subtle way of making a statement. I am glad they get away with it.

    Now it’s time to go.

    Bill Howard

  2. Anonymous said April 17, 2006, 11:54 pm:


    1. Thanks a lot for the informative comment. I will correct the post to say Daylight Saving Time.

    2. The Dine Nation factoid is very interesting. Hope someone from Microsoft is reading it.

  3. Anonymous said September 30, 2006, 1:12 am:

    I had to reach back in time to follow up on this thread, but then this comment is about time.

    I just read an interesting W3C Working Draft, Time Ontology in OWL that provides us with insites to the challenges of accurately expressing temporal information. Time Ontology in OWL

    “presents an ontology of temporal concepts, OWL-Time (formerly DAML-Time), for describing the temporal content of Web pages and the temporal properties of Web services. The ontology provides a vocabulary for expressing facts about topological relations among instants and intervals, together with information about durations, and about datetime information…A use case for meeting scheduling is also shown. In the appendix we also describe a time zone resource in OWL we developed for not only the US but also the entire world, including the time zone ontology, the US time zone instances, and the world time zone instances. “

    For those who have the time to read about time, I want to you to be forewarned that this document is not an easy read. Time is a complex issue that takes time to understand. The reader may have to take the time to read certain portions multiple times since the text is laced with statements such as this:

    “Intervals are, intuitively, things with extent and instants are, intuitively, point-like in that they have no interior points. It is generally safe to think of an instant as an interval with zero length, where the beginning and end are the same.”

    Relative to time zones and daylight saving time, I have now learned that:

    “If we were to conflate time zones (i.e., geographical regions) and time standards, it would likely result in problems in several situations. For example, the Eastern Standard zone and the Eastern Daylight zone are not identical, since most of Indiana was on Eastern Standard time all year. The state of Arizona and the Navajo Indian Reservation, two overlapping geopolitical regions, have different time standards during the daylight saving times — one is Pacific and the other is Mountain.

    Time standards that seem equivalent, like Eastern Standard and Central Daylight, should be thought of as separate entities. Whereas they function the same in the time ontology, they do not function the same in the ontology that articulates time and geography. For example, it would be false to say those parts of Indiana shifted in April from Eastern Standard to Central Daylight time.”

    All this makes me wonder if I have appeared to be a simpleton to my colleagues in India when I write from my geographical location in Phoenix, Arizona that I would like to propose that we have a conference call at 6:00 am PDT / 6:30 pm IST. This must seem even more confusing, when I consider that starting on October 30, 2006, in order to schedule the call for the same time period I shall have to write “6:00 am MST / 6:30 pm IST.”

    I do think that is incorrect to write “6:00 am PDT” since Arizona is not in the geographic Pacific Time zone. I really should write “6:00 am MST” all year long, but I worry that it would be misread by others in the US as “MDT.” then the scheduling would get confused and someone might miss the call.

    I never worried about this before, but now that the W3C has me thinking about such things, I am quite concerned.


  4. Anonymous said October 1, 2006, 9:25 am:

    Thanks Bill for the update. The W3C OWL is a tough read. But i think it is a great initiative. Unfortuntately this is buried in the comments.