When were the North American time zones established?
History of time in the United States
The history of standard time in the United States began November 18, 1883, when United States and Canadian railroads instituted standard time in time zones. Before then, time of day was a local matter, and most cities and towns used some form of local solar time, maintained by some well-known clock (for example, on a church steeple or in a jeweler's window). The new standard time system was not immediately embraced by all.
Time zone
Timekeeping on the American railroads in the mid-19th century was somewhat confused. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had a clock for each railroad, each showing a different time.
Charles F. Dowd proposed a system of one-hour standard time zones for American railroads about 1863, although he published nothing on the matter at that time and did not consult railroad officials until 1869. In 1870 he proposed four ideal time zones (having north–south borders), the first centered on Washington, D.C., but by 1872 the first was centered on the meridian 75° W of Greenwich, with geographic borders (for example, sections of the Appalachian Mountains). Dowd's system was never accepted by American railroads. Instead, U.S. and Canadian railroads implemented a version proposed by William F. Allen, the editor of the "Traveler's Official Railway Guide". The borders of its time zones ran through railroad stations, often in major cities. For example, the border between its Eastern and Central time zones ran through Detroit, Buffalo, Pittsburgh, Atlanta, and Charleston. It was inaugurated on Sunday, , also called "The Day of Two Noons", when each railroad station clock was reset as standard-time noon was reached within each time zone. The zones were named Intercolonial, Eastern, Central, Mountain, and Pacific. Within a year 85% of all cities with populations over 10,000, about 200 cities, were using standard time. A notable exception was Detroit (which is about halfway between the meridians of eastern time and central time) which kept local time until 1900, then tried Central Standard Time, local mean time, and Eastern Standard Time before a May 1915 ordinance settled on EST and was ratified by popular vote in August 1916. The confusion of times came to an end when Standard zone time was formally adopted by the U.S. Congress in the Standard Time Act of March 19, 1918.