Does anyone know how the boundaries for Time Zones in the US are/were determined? In some places it looks like state lines are followed somewhat and other places the line seems to jog out of the way to purposely include or exclude some small portion of a state. It looks like someone went out of the way to include 5% of Indiana in a different time zone.

Anybody know? Do mountain ranges play a role in determining where the lines go in the North central and western states?

Bill

I wonder if they actually drew them so they could accomodate large population centers so that a city wouldn't be divided between two time zones.

Can you imagine walking across the street and having to set your watch back? Good for keeping curfew if you're a teenager living at home!

a couple quick searchs revieled some neat sites here is one. Seem the DOT has control of the boundaries and they are based on easy of commerce.
http://aa.usno.navy.mil/faq/docs/us_tzones.html

http://webexhibits.org/daylightsaving/d.html

The basic time zone division is based on 360 degrees / 24 zones giving 15 degrees of longitude between time zones.

I assume that where the natural boundaries fell near to state lines that somebody decided it made sense to make the boundary detour a little. If the line cut through the middle part of a state, then in many cases it follows county lines. The boundary between central and mountain zones in Nebraska does that, except in Cherry Co. in the north where it just divides the county in two (very big county!).

I think Sven's suggestion about minor detours to account for population centers makes sense. The boundary you mentioned in Indiana follows county lines and puts the northwestern corner into CST. I imagine somebody thought it made sense for Hammond, Gary and the other urban stretch of Indiana along Lake Michigan to be in the same time zone as Chicago. By the way, doesn't Indiana also have the peculiarity that those counties in CST use daylight savings in summer but the the rest of the state doesn't?

Looking at the boundaries on a map, it does seem as though other features were sometimes followed. Look at the Florida panhandle and the boundary follows the Apalachicola River, (flowing south from the Chattahoochee and Lake Seminole at the GA/AL border, itself the EST/CST boundary).

The far western tip of Texas is an interesting peculiarity. At some point in history did somebody there decide that El Paso was far enough west from the rest of Texas that it should go into the mountain zone?

The situation is much simpler in the U.K. We're so small that the whole country is in one time zone!

Here's a link to a map that shows how the time zone lines do not follow along state lines. You can see how some states are divided oddly, which was what prompted my question. Look closely at Indiana and you can see just the slightest bit in the NW corner is different from the rest of the state.
http://www.time.gov/

I found an article on Indiana specifically:
What time is it in Indiana?

I'm still confused


Bill

The above link to Navy website contains the phrase ' Furthermore, under the law, the principal standard for deciding on a time zone change is the "convenience of commerce." '.

This makes it clear that the actual boundaries have more to do with commerce than any thing else.

Northern Indiana has most of it's commerce with the Chicago area so it makes sense to share a common time.

The Upper Peninsula of Michigan is supposed to be in the Eastern time zone to match the rest of the state, however each county that directly touches, and trades with, Wisconsin is in the Central zone.

I live in East Central Indiana. We donot observe daylight savings time. Part of Northern as well as Southern Indiana do. Every time the State Legislature tries to pass a law to require all of the state to do one or the other, it gets shot down. Some people get down right nasty over the issue. Personally, I don't care which way they do it, I just wish the whole state would do the same thing. DST would have it's advantages for my work situation. I remember when I was a kid and all of Indiana observed DST. I hated going to bed in September when it was still light outside!

Fred,

As per my "What Time" link above it seems like there are actually 3 areas in the same state with different rules related to time?




Boy, that's got to be confusing!

Bill

[This message has been edited by Bill Addiss (edited 03-12-2003).]

Interesting links. So the situation in Indiana is even more complex than I first thought!

In Western Europe the time zones just follow national boundaries: http://www.worldtimezone.com/time-europe.htm

Britain went on to permanent daylight savings during WWII as well. There was a similar experimental period of staying an hour ahead in the late 1960s/early 1970s.

There is a lot more interesting background (including details of each U.S. state) at this site: www.greenwichmeantime.com


[This message has been edited by pauluk (edited 03-13-2003).]

Bill, One of the most basic reasons that Northwest Indiana is in the same Time Zone with Chicago is because so many residents who live in Indiana work in Chicago. This can be accomplished with only a 45 minute commute each way. Could you imagine what it would be like if you (theoretically) had to change your watch every day as you were driving to work and then again when you were driving home??

To add a little more complexity to Time Zone Plan. There are areas on the other side of the planet that have Half-hour Time Zones.

Actually, on this side of the globe, There is
Newfoundland, which as 1/2 Hr off Atlantic.

Howewvet there is some counties in the mideast with a 15 minute offset.

In Canada Saskatchewan is always on the same time, the result being in the winter, I get 5 time zone feeds of CBC on satellite. in the summer, the Regina CBC is on the same zone as one of the other cities, knocking me down to four Time zones of CBC to choose form.

Pearlfish, There are a lot of people who live in Richmond and work in Ohio who deal with the DST difference every summer. I just wish Indiana was uniform with their time zone.

Fred, it sounds like the folks in Richmond need to slip fatter envelopes to their politicians. If you hold more voter registration drives in your local cemetaries like we do, you might not have those problems.