Why aren’t they perfectly longitudinal?
Politics.
Political reasons, primarily. In the sense that, wherever possible, the political region involved should be in the same time zone for ease of conducting business and other such activities.
In many cases in the USA, the Time Zone lines run along state borders, especially if the shape of the state is more vertical than horizontal. In a “horizontal” state (e.g., Tennessee) near what would be an otherwise unobstructed line along state borders running longitudinally, Tennessee has the unfortunate position of being in two time zones. The zone line is crossed on I-40 west of Knoxville and East of Crossville.
In other places around the globe, similar considerations are at play. Some countries have opted for time zones that don’t fit the longitudinal pattern and are thus “oddballs” in the overall scheme.
Bear in mind that time zones were created for business purposes to start with and are arbitrary conveniences. Time used to be reckoned locally from noon (sun passing overhead) so everywhere had a different time. Rapid transit in the railroad era urged people to “standardize” time. They did. But it was far from simple.
Mostly to avoid splitting up areas on land that have the same cultures, governmental structures, and economies. Time zones in the U.S. and Canada generally follow state and provincial boundaries, although there are some oddities for historic reasons.
Different watch brands. Some run a little slower.
Thanks, Exanpo Mapcase… I was just about to bring up those oddities. Anyone know the reasons why there’re still some wild deviations, even within countries, states, and provinces?
Being ex-military and working on the Zulu clock. 24 hours = 24 time zones. Pretty cut and dry.
Why the lines are placed where the are? Maybe because of elevations? Deviations in the terrain of the globe will cause delays in the sun “rising” over mountaneous terrains.
Try here:
http://physics.nist.gov/News/Releases/questions.html
Politics. 
Just to mention on obvious example. The area of NW Indiana wants to be on the same time zone as Chicago, for perfectly valid reaons that there is no point to just calling “politics”. The zones are there to serve human needs and they are adjusted for that purpose. Some of the adjustments are not always comprehensible. Why the west end of the Florida panhandle is on central time or why a part of eastern Oregon is on mountain time is not clear to me. (It does mean that for one hour every year, the time in (part of) an Atlantic seaboard state is the same as time in (part of) a Pacific seaboard state).
It was indeed the railroads that enforced time zone standardization. More precisely, they set up standard time zones (it was called, “railroad time”) and made their schedules accordingly. People were free to ignore it, but not if they wanted to catch their train and eventually it became standardized.
China uses one time zone, although it is big enough for three. And Russia uses 9, one of which is the same time as, but a day later than, the western Aleutians.
Convenience and knowing when to catch a train wasn’t the impetus behind standardized “railroad time.” Safety was the reason - the railroads needed to synchronize themselves to each other so there wouldn’t be disasters caused by two trains attempting to go in different directions on the same track, which was not unheard of as until the 1860’s, there were 300 or so city-based different time zones in the US.
Idaho is involved with this sort of thing twice. The northern end of the state is in the Pacific Time zone.
I have always understood this to be for local convenience. The majority of people in northern Idaho have more to do on a day-to-day basis with Spokane and other Pacific Time regions in Washington than they do with Boise in the Mountain Time zone. It’s the same story with eastern Oregon where Boise is the local population center.
You’re a pain, Aesiron. 
Surprisingly, my books on time have little to say about the particulars of the origin of U.S. time zones.
The standard history, Revolution in Time: Clocks and the Making of the Modern World by David S. Landes, mentions that Britain consolidated its local times as early as 1847, when the British Railway Clearing House recommended that everybody use Greenwich time “as soon as the Post Office permits them to do so,” which it did by the end of that year.
He does say that “trains moved too fast for [local time], continually exposing passengers and crew to discrepancies and confusions” indicating that convenience was at least as much a factor as safety.
James Jesperson and Jane Fitz-Randolph in From Sundials to Atomic Clocks seem to agree:
This goes along with what I’ve read elsewhere. Before the advent of “Union” stations, each railroad had its own station in a city, each on its own time. A traveler would normally have to switch railroads several times in a long trip and would have to know the particular railroad time for each in order to make connections.
Getting the entire world to agree on international time zones was a long and contentious process, which is detailed in an enjoyable but very quirky book called Time Lord by Clark Blaise, about the efforts of Sir Sandford Fleming to get a world conference established. The account of the 1884 prime Meridian Conference in Washington is practically surreal in its bizarre politics.
Someone brought up time zone oddities.
Some time zones (India for example) are NOT based on a one hour difference but on a 30 minute difference.
Proably the weirdest time zone oddity is Chatam Island (located to the East of New Zealand) has a time zone with a 15 minute difference.
A GREAT site for finding the time anywhere in the world is:
http://www.timeanddate.com/worldclock/full.html
Please visit that site. It is VERY impressive.
Thanks, Exapno Mapcase… you too, wolf_meister
/. I have that site bookmarked now.
Indiana, where I live, has to be the king of the time zone “oddity” in the United States. We never change times in Indianapolis, meaning part of the year we are on Chicago time and part of the year on NY time. However, part of the state (I believe Evansville and up around Chicago) does change to stay with Central daylight time. Then I think the part of the state around Louisville changes to stay on Easteren Daylight time. Every single year there is legislation introduced to change to Daylight Savings Time and every single year it is defeated. My guess this will continue until the Gen Xers start making some headway into having some power in the state. There are good reasons for changing. Businesses complain because if they do business out of state, no one can ever figure out what time it is here. The standard reply to this is, “Why should we change for everyone else.” or “How hard could it be.” Its not hard if you follow the same rules as every other state, but to force people to learn the exceptopn is just a pain. Or people think it has something to do with the politicians wanting us to “copy New York” ??? What??? Or they give answers about how they don’t need anymore daylight because they wake up early. All very lame answers, in my opinion.
I think only six states don't change times. Hawaii and Alaska are two. Not contiugous states, so really makes sense. Arizona is another. They argue that the last thing they need in summer is "more daylight hours", which seems somewhat logical. OF course its not really more daylight, you're just changing what time of day the daylight is occuring. Somehow, though, this works out so that it really saves money not to change in that state because of power usage issues. Indiana makes the fourth, no good excuse. Not sure what the two other states are, but I believe they are also out West and use arguments similar to what Arizona does. So Indiana refuses to change basically because they don't want to. The other states use some sort of logical reasoning.No, there’s only three: Hawaii, Arizona and Indiana. Hawaii doesn’t change because it really doesn’t make sense to have daylight saving time in the tropics. The length of the day doesn’t vary that much.
Oh yes, another anomaly is that the Navajo Indian Reservation in Arizona does change to MDT, while the rest of the state does not. Technically, this is not legal, as there is a law that requires that all parts of a state in the same time zone either change or not change as a unit. But that law doesn’t keep anyone from setting their clock to whatever time they want; it just mandates the legal time. By the same rule, the Indiana suburbs of Louisville also can’t legally go to daylight time, but everyone there sets their clock forward anyway.
I’m not sure if it’s still true or not, but I know that about 10 years ago or so Grand Canyon National Park also changed it’s time while the rest of the state didn’t.
As dtilque points out, Alaska does indeed change from Standard time to Daylight Savings time and back again.
Portugal has changed its time zone . Although it is in mainland Europe it is realy too far west for it to have have the same time zone as the rest of the continent. So they decided a few years ago to swich to the same time zone as the UK and Ireland (GMT)
It is defeated in part because of the great power held by Gary. If Indiana goes to a single time zone (which is the only thing the state can legally do, if I recall), then the entire state, by Federal law, must go with the Eastern time zone, since the time zones are set up by the Feds.
Have you ever tried living in the summer on EDT in Indiana? It’s a serious pain in the ass. I hope you like getting up before sunrise. If we should be in any time zone, it should be the central zone, not the eastern.
I do business with companies worldwide and they have no trouble. Of course, they’re not a bunch of penny-ante lightweights, either. Eli Lilly seems to be able to get things to work, as does Roche. I guess pharmaceuticals and biotech firms attract generally more intelligent people.
The problem is that all proposals floated end up with Indiana adopting EDT. We are in the wrong locale for that to work out properly. Quick, what is the major economic center closest to Indiana? Chicago beats all other contenders. So, the only intelligent choice is central zone.