I found this on the subject, interesting reading.
Not sure how to post so hope this works.

Cheers,
Bordello

If the link doesn't work, here it is.
http://answers.yahoo.com/question/index?qid=20071018230735AA2wieR

I remember as a child that AZ did try it one year.  And what a disaster it was.  The sun didn't set until after 9 and it wasn't dark until after 10.  Thus it was hard to get kids to go to bed since it was still light.  And to really show my age, the drive in movies couldn't even start until after 10 either and so no one was going as that was too late.  

Daylight savings was started for the farmers basically so they could have more daylight to harvest their crops.  But since Arizona already had plenty of daylight during spring and summer there was no need to do it but we did try it once.  

Hope that helps.  There is talk of trying to get rid of it for the entire country as we are no longer farmer based in our economy.  

Misty
.
Here is that question poised to our local newspaper:

Q: Why doesn't Arizona practice daylight-saving time?
A: Arizona, along with Hawaii, Puerto Rico, the Virgin Islands, American Samoa and parts of Indiana, remains steadfastly attached to Standard Time. The Navajo Nation, however, with the exception of some state offices, does recognize daylight-saving time. In 1967, Arizona adopted daylight saving to go along with the Uniform Time Act, which tried to put the entire nation on one time system. But, after a summer of sunsets that didn't come till nearly 9 p.m., residents realized they needed another hour of evening sun the way they needed more snakes, scorpions and snowbirds. So Arizona abandoned the plan.

And here is another site giving the answer as to isn't it federal law:

You might ask, isn't the changing of the clocks a federal law? The answer is that although Daylight Saving Time was established by federal law in 1986, a state or area may choose not to observe it. Other areas in the U.S. that don't observe Daylight Saving Time are Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands. In Arizona, we just don't need another hour of sunlight!

-- Modified on 3/9/2008 7:55:51 AM

that after last night I have to wait an hour less to go to Phoenix, but you guys have to wait the same amount of time for me to get there?

Wierd.

It's our dim witted mayor

We tried it. The first spring it was to take effect the mayor had a midnight appointment. He showed up, the clock got turned ahead 1 hr and he paid and left without service. Hey he figured an hour is an hour. This happened 3 years in a row before he figured it out and ended daylight savings time in Poon Valley

daylight = heat

An extra hour of daylight means an extra hour of heat. We don't want it to be 110 degrees at midnight.

Now, we switch to PDT this time of year, so techincally we are on Daylight Saving Time.