As DST Ends – 5th Time Zone Erupts Briefly in the U.S.

Posted On: March 10, 2015

Over the weekend, daylight savings time ended. As I was watching the time change between all the time zones, I noticed something interesting. Take a look at the image below which was made after the Mountain Standard Time (MST) and before the Pacific Standard Time (PST) time change during spring ahead. Do you notice something interesting in the below grid? 

The cities above, Portland, Oregon (PST), Phoenix, Arizona and Boise, Idaho (MST), Houston, Texas (CST) and
Tampa, Florida (EST), represent all four time zones.

Of course, we all know, as shown in the image to the right, there are supposed to be only four time zones in the continental USA. 

But, by the looks of it, this time grid suggests that there are FIVE not FOUR time zones in the continental USA. The first time I saw it, I felt my eyes were playing tricks on me. Why would each hour be represented? If an hour is missing then, there should be two hours between the time zone that just ‘changed’ and the time zone that changed an hour ago, as in the image below. The image below shows the EST leap forward. As the East Coast cities lept forward and the Central Time Zone hadn’t yet changed there was a two hour time difference, keeping four time zones. So, then, why were there five time zones shown during the MST leap forward? Any ideas? 

The cities of San Diego, Salt Lake City, Omaha, and Fairfax which represent all four American time zones,
are compared against the static IST time zone.

The answer, while perplexing is simple. It is because most parts of Arizona doesn’t observe DST.  And, due to that, their time doesn’t change. Amazingly since there is no change for these areas, this creates an ‘imaginary’ fifth time zone for about 59 minutes and 59 seconds until the PST leaps forward. I am eager to see what happens in the fall back

While the time change is a national mandate, certain areas like Arizona are exempt. Other states also are exploring exemption. I will share more on that in future posts. 

Time change, time management in professional settings and other business dos and don’ts with Americans are explored, demonstrated and practiced in US Business Culture Orientation programs to expats planning to go onsite or who are already onsite. See here for more details. 

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