An old chestnut
goes like this:
Two friends are talking on the phone.
One lives in a west-coast state of the United States.
The other lives in an east-coast state of the United States.
They realize that it is the same time in both places. How is this possible?
One friend lives in southeastern Oregon, near Boise, Idaho. This area is in the Mountain time zone. The other lives in the Florida panhandle, south of Alabama. This is in the Central time zone. Normally these areas are one hour apart, so when it is 6:00 for the friend in Florida, it is 5:00 for the friend in Oregon. However, when Daylight Savings Time ends, it does so at the same time of day in each time zone. For one hour, after the Central time zone has fallen back to standard time, it is the same time there as in the Mountain time zone where they have not yet changed the clocks back.