Following Sandford Fleming’s proposal, Canada, which spans almost 90 degrees of longitude, was first divided into seven time zones: Newfoundland, the Atlantic, the East, the Centre, the Rockies, the Pacific and Yukon (only in 1973 did Yukon adopt Pacific standard time).
Cities within a single time zone kept the same time. Boundaries between time zones were established gradually. For greater convenience in some places, time zone boundaries were modified to reproduce geographical and political boundaries.
Thus, Quebec’s vast territory was divided into two time zones from 1963 to 1969.
Then, to simplify communications, the boundary was established along the 68th degree of longitude and the province was unified as one time zone.