If every community used a different time, travellers would be confused and many other problems would be created. To avoid all such problems, standard time zones were established. These zones were set up so there would be a difference of one hour between a place on the eastern edge of a time zone and a place on the western edge if each were on its own local time. But under the time zone system, each of these places is not on its own local time. The local time at the meridian (line) of lingitude that runs through the middle of the zone is used by all places within the zone. Thus, time throughout the zone is the same.
Fact file
The United States and Canada each have six standard time zones. Each zone uses a time one hour different from its adjacent zones.
resources: Tell me what (Chancellor Press)
image 1: http://www.physicalgeography.net/fundamentals/images/world_time2.gif
iamge 2: https://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Central_Time_Zone_CST.png/1200px-Central_Time_Zone_CST.png