The U.S. time zones, from east to west, are Eastern, Central, Mountain and Pacific time. Eastern zone is the furthest ahead, with an hour difference between each zone. Alaska and Hawaii have their own time zones.
Canadian time zones, from east to west, are Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific. Newfoundland is 1.5 hours ahead of Eastern time, while Atlantic time is one hour ahead of Eastern time.
In general, areas of the U.S. and Canada that share the same approximate longitude share the same time zone. However, if you travel east or west in either country, you will eventually reach another time zone.
Railroad operation required the United States and Canada to keep standard time and enforce standard time zones. Standard time began on Nov. 18, 1883. U.S. time zones were formally enshrined in law on March 19, 1918.
