standard time

standard time, civil time used within a given time zone. The earth is divided into 24 time zones, each of which is about 15° of longitude wide and corresponds to one hour of time. Within a zone all civil clocks are set to the same local solar time. Adjacent zones typically differ by a whole hour, although there are instances, such as in Newfoundland and South Australia, of half-hour zones. Standard time is based on universal time. Standard time was largely the creation of the Canadian railway engineer Sir Sandford Fleming (1827–1915). Its establishment in the United States was mainly due to the efforts of the educator Charles Dowd and William Allen, secretary of the American Railroad Association. Standard time officially came into existence after a 19-nation White House meeting in 1884, with the prime meridian established at Greenwich, England. In the United States, time zones are regulated by the Dept. of Transportation.