At 09:18 AM 3/15/2016, Paul_Koning@Dell.com wrote:

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A limitation of that format is that it doesn't show that DST rules vary from one country to another, so while there is a whole stripe of EST/EDT, the transition may not occur all at once across that whole stripe.

Paul: Yes, that is a significant limitation. On the exceptions page (http://ontimezone.com/exceptions.php#dst) it says "...most North American locations follow DST (not necessarily on the same schedule)." Then it lists the exceptions. I haven't found a simple, intuitive way to present that data on the map. I've tried, and it just seems to further obfuscate an already confusing topic. Within the limited scope of OnTimeZone.com (http://ontimezone.com/images/na.gif) all DST observance is on the same schedule with the sole exception of that portion of Mexico outside the states of Sonora and Quintana Roo (which do not observe DST) and the poorly defined areas near the US border (20km + various specific locales), which observe DST on the US schedule. Steve Jones OnTimeZone.com