There are six time zones in Canada. From west to east the main time zones are: Pacific, Mountain, Central, Eastern and Atlantic. The island of Newfoundland observes a sixth time: it decided to set its clock at the halfway point of its time zone or 3 hours and 30 minutes behind Greenwich time instead of four hours (which would be Atlantic time). Finally, many parts of the country do not observe the official hour, choosing instead to adopt the time in a neighbouring zone in order to facilitate trade between adjacent regions. This is particularly common in eastern British Columbia which often uses Mountain time rather than the Pacific time of the rest of the province.