Canada is divided into six time zones, based on proposals by Scottish Canadian railway engineer Sir Sandford Fleming, who pioneered the use of the 24-hour clock, the world's time zone system, and a standard prime meridian. Most of Canada operates on standard time from the first Sunday in November to the second Sunday in March and daylight saving time the rest of the year.
The National Research Council (NRC) maintains Canada's official time through the use of atomic clocks. The NRC makes time servers available for direct synchronization with computers. The Canadian Broadcasting Corporation has aired a daily time signal, the National Research Council Time Signal, since 5 November 1939.
The Government of Canada recommends use of the 24-hour clock, which is widely used in contexts such as transportation schedules, parking meters, and data transmission. Speakers of Canadian French have fully adopted this system, but many users of Canadian English use the 12-hour clock in everyday speech, even when reading from a 24-hour display, similar to the use of the 24-hour clock in the United Kingdom.
Four Canadian cities, by local ordinance, used Daylight Saving Time in 1916. Brandon, Manitoba on April 17 became the first place in the world to use it. It was followed by Winnipeg on April 23, Halifax on April 30, and Hamilton, Ontario on June 4.
Daylight saving time is currently observed in all ten provinces and three territories but with several exceptions in several provinces and Nunavut, including most of Saskatchewan, which despite geographically being in the Mountain Time Zone observes year-round CST. Under the Constitution of Canada, laws related to timekeeping are a purely provincial matter. In practice, since the late 1960s DST across Canada has been closely or completely synchronized with its observance in the United States to promote consistent economic and social interaction. When the United States extended DST in 1987 to the first Sunday in April, all DST-observing Canadian provinces followed suit to mimic the change.
The latest United States change (Energy Policy Act of 2005), adding parts of March and November starting in 2007, was adopted by the various provinces and territories on the following dates:
|c.c.*||coordinates*||TZ*||comments*||UTC offset||UTC offset DST||Notes|
|CA||+4734-05243||America/St_Johns||Newfoundland Time, including SE Labrador||-03:30||-02:30|
|CA||+4439-06336||America/Halifax||Atlantic Time - Nova Scotia (most places), PEI||-04:00||-03:00|
|CA||+4612-05957||America/Glace_Bay||Atlantic Time - Nova Scotia - places that did not observe DST 1966-1971||-04:00||-03:00|
|CA||+4606-06447||America/Moncton||Atlantic Time - New Brunswick||-04:00||-03:00|
|CA||+5320-06025||America/Goose_Bay||Atlantic Time - Labrador - most locations||-04:00||-03:00|
|CA||+5125-05707||America/Blanc-Sablon||Atlantic Standard Time - Quebec - Lower North Shore||-04:00||-04:00|
|CA||+4531-07334||America/Montreal||Eastern Time - Quebec - most locations||-05:00||-04:00|
|CA||+4339-07923||America/Toronto||Eastern Time - Ontario & Quebec - most locations||-05:00||-04:00|
|CA||+4901-08816||America/Nipigon||Eastern Time - Ontario & Quebec - places that did not observe DST 1967-1973||-05:00||-04:00|
|CA||+4823-08915||America/Thunder_Bay||Eastern Time - Thunder Bay, Ontario||-05:00||-04:00|
|CA||+6344-06828||America/Iqaluit||Eastern Time - east Nunavut - most locations||-05:00||-04:00|
|CA||+6608-06544||America/Pangnirtung||Eastern Time - Pangnirtung, Nunavut||-05:00||-04:00|
|CA||+744144-0944945||America/Resolute||Central Time - Resolute, Nunavut||-06:00||-05:00|
|CA||+484531-0913718||America/Atikokan||Eastern Standard Time - Atikokan, Ontario and Southampton I, Nunavut||-05:00||-05:00|
|CA||+624900-0920459||America/Rankin_Inlet||Central Time - central Nunavut||-06:00||-05:00|
|CA||+4953-09709||America/Winnipeg||Central Time - Manitoba & west Ontario||-06:00||-05:00|
|CA||+4843-09434||America/Rainy_River||Central Time - Rainy River & Fort Frances, Ontario||-06:00||-05:00|
|CA||+5024-10439||America/Regina||Central Standard Time - Saskatchewan - most locations||-06:00||-06:00|
|CA||+5017-10750||America/Swift_Current||Central Standard Time - Saskatchewan - midwest||-06:00||-06:00|
|CA||+5333-11328||America/Edmonton||Mountain Time - Alberta, east British Columbia & west Saskatchewan||-07:00||-06:00|
|CA||+690650-1050310||America/Cambridge_Bay||Mountain Time - west Nunavut||-07:00||-06:00|
|CA||+6227-11421||America/Yellowknife||Mountain Time - central Northwest Territories||-07:00||-06:00|
|CA||+682059-1334300||America/Inuvik||Mountain Time - west Northwest Territories||-07:00||-06:00|
|CA||+4906-11631||America/Creston||Mountain Standard Time - Creston, British Columbia||-07:00||-07:00|
|CA||+5946-12014||America/Dawson_Creek||Mountain Standard Time - Dawson Creek & Fort Saint John, British Columbia||-07:00||-07:00|
|CA||+4916-12307||America/Vancouver||Pacific Time - west British Columbia||-08:00||-07:00|
|CA||+6043-13503||America/Whitehorse||Pacific Time - south Yukon||-08:00||-07:00|
|CA||+6404-13925||America/Dawson||Pacific Time - north Yukon||-08:00||-07:00|