Different time zones in the history of the United States
The evolution of United States standard time zone boundaries from 1919 to 2024 in five-year increments.Plaque in Chicago marking the creation of the four time zones of the continental US in 1883Colorized 1913 time zone map of the United States, showing boundaries very different from todayMap of U.S. time zones during between April 2, 2006, and March 11, 2007. The current situation is different only in that six Indiana counties have since been moved from the Central time zone to the Eastern time zone.
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 standard time system was not immediately embraced by all. Standard time in time zones was established in U.S. law in the Standard Time Act on March 19, 1918, at which time daylight saving time was also instituted.
Use of standard time gradually increased because of its obvious practical advantages for communication and travel. Standard time in time zones was established in U.S. law in the Standard Time Act on March 19, 1918.[1][2] The act established daylight saving time, which was and is a contentious idea. Daylight saving time was repealed in 1919, but standard time in time zones remained in law, with the Interstate Commerce Commission (ICC) having the authority over time zone boundaries. Daylight time became a local matter; ultimately, it was reinstated nationally early in World War II and was continuously observed until the end of the war. After the war its use varied among states and localities. The Uniform Time Act of 1966 provided standardization in the dates of beginning and end of daylight time in the U.S. but allowed for local exemptions from its observance.
Time zone boundaries have changed greatly since their original introduction, and changes still occasionally occur. DOT issues press releases when these changes are made. Generally, time zone boundaries have tended to shift westward. Places on the eastern edge of a time zone can effectively move sunset an hour later (by the clock) by shifting to the time zone immediately to their east. If they do so, the boundary of that zone is locally shifted to the west; the accumulation of such changes results in the long distance term westward trend. The process is not inexorable, however, since the late sunrises experienced by such places during the winter may be regarded as too undesirable. Furthermore, under the law, the principal standard for deciding on a time zone change is the "convenience of commerce". Proposed time zone changes have been both approved and rejected based on this criterion, although most such proposals have been accepted.
Railway time
Map of 1884/5 explaining the time zones used on American railway lines.This cartoon appeared on the cover of Life magazine, January 3, 1884
One of the first reported incidents which brought about a change in how time was organized on railways in the United States occurred in New England in August 1853. Two trains heading towards each other on the same track collided in the Valley Falls train collision because the train conductors had different times set on their watches, resulting in the death of 14 passengers. Railway schedules were coordinated in New England shortly after this incident[3] Numerous other collisions led to the setting up of the General Time Convention, a committee of railway companies to agree on scheduling.[4]
In 1870 Charles F. Dowd, who was unconnected with the railway movement or civil authorities, proposed A System of National Times for Railroads, which involved a single time for railways but the keeping of local times for towns. Although this did not find favor with railway managers, in 1881 they agreed for the idea to be investigated by William Frederick Allen, who was the secretary of the General Time Convention and managing editor of the Travellers' Official Guide to the Railways. He proposed replacing the 50 different railway times with five time zones. He eventually persuaded the railway managers and the politicians running the cities that had several railway stations that it was in their interests to speedily adopt his simpler proposals, which aligned the zones with cities' railroad stations. In doing so, they would pre-empt the imposition of more costly and cumbersome arrangements by different state legislators and the naval authorities, both of whom favored retention of local times.[4]
On 11 October 1883, a convention of railroad executives met in Chicago at the General Time Convention (latter renamed the American Railway Association) and agreed to the implementation of five time zones in North America, using Greenwich Mean Time as a basis.[5][6] Right to the end there was opposition expressed by many smaller towns and cities to the imposition of railway time. For example, in Indianapolis the report in the daily Sentinel for November 17, 1883, protested that people would have to "eat sleep work... and marry by railroad time".[7] However, with the support of nearly all railway companies, most cities and influential observatories such as Yale and Harvard, this collaborative approach led to standard railway time being introduced at noon on November 18, 1883. This consensus held and was incorporated into federal law in 1918.[4][8][9]
Standard time and war time
"War Time" redirects here. This usage refers to the changes of the US War Time Act, not a general period of war.
Daylight saving time (DST) was established by the Standard Time Act of 1918. The act was intended to save electricity for seven months of the year, during World War I.[10] DST was repealed in 1919 over a presidential veto,[11] but standard time in time zones remained in law, with the Interstate Commerce Commission (ICC) having the authority over time zone boundaries. Daylight time became a local matter.
During World War II, Congress enacted the War Time Act (56 Stat. 9) on January 20, 1942. Year-round DST was reinstated in the United States on February 9, 1942, again as a wartime measure to conserve energy resources.[12] This remained in effect until after the end of the war. After V-J Day, the word 'war' and the middle letter 'W' were changed to 'prevailing' and 'P', but the advance in the clock was not reverted. The Amendment to the War Time Act (59 Stat. 537) ended DST as of September 30, 1945. During this period, the official designation War Time was used for year-round DST. For example, Eastern War Time (EWT) would be the equivalent of Eastern Daylight Time during this period.
Local-option daylight saving time
Time zone map of 1948. The borders between zones are slightly different to those of today.
From 1945 to 1966 U.S. federal law did not address DST. States and cities were free to observe DST or not, and most places that did observe DST did so from the last Sunday in April to the last Sunday in September. In the mid-1950s many areas in the northeastern United States began extending DST to the last Sunday in October. The lack of standardization led to a patchwork where some areas observed DST while adjacent areas did not, and it was not unheard of to have to reset a clock several times during a short trip (e.g., bus drivers operating on West Virginia Route 2 between Moundsville, West Virginia, and Steubenville, Ohio, had to reset their watches seven times over 35 miles).[13]
In summer 1960 April–October Daylight Time was nearly universal in Pennsylvania, Maryland, Delaware and states east and north of there. In Minnesota, Iowa, Missouri, Kentucky and Virginia and states north and east of there, some areas used DST and some did not. Except for California and Nevada, which had April–September Daylight Time, 99% of the rest of the country used Standard Time year-round. (The Official Guide says "State law prohibits the observance of "Daylight Saving" time in Kentucky but Anchorage, Louisville and Shelbyville will advance their clocks one hour from Central Standard time for the period April 24 to October 29, inclusive.")
Uniform Time Act
In the mid-1960s the airline and other transportation industries lobbied for uniformity of DST dates in the United States. The federal Uniform Time Act became law on April 13, 1966, and it mandated that DST begin nationwide on the last Sunday in April and end on the last Sunday in October, effective in 1967. The act explicitly preempted all previously enacted state laws related to the beginning and ending of DST effective in 1966. Any state that wanted to be exempt from DST could do so by passing a state law, provided that it exempted the entire state, and Alaska, Arizona, Hawaii, Indiana, and Michigan chose to do so. However, Alaska, Indiana, and Michigan subsequently chose to observe DST.
The law was amended in 1972 to permit states that straddle a time zone boundary to exempt the entire area of the state lying in one time zone. Indiana chose to exempt the portion of the state lying in the Eastern Time Zone; however, that exemption was eliminated in 2006, and the entire state of Indiana now observes DST, leaving Arizona (with the exception of the Navajo Nation) and Hawaii as the only two states not to observe DST.
In response to the 1973 energy crisis, DST began earlier in both 1974 and 1975, commencing on the first Sunday in January (January 6) in the former year and the last Sunday in February (February 23) in the latter. The extension was not continued due to public opposition to late sunrise times during the winter months. In 1976, the United States reverted to the schedule set in the Uniform Time Act.[14]
Daylight saving time extensions
On July 8, 1986, President Ronald Reagan signed the Federal Fire Prevention and Control Act of 1986 into law that contained a daylight saving rider authored by Senator Slade Gorton.[10] The starting date of DST was amended from the last Sunday of April to the first Sunday in April effective in 1987, extending DST three weeks; DST continued to end on the last Sunday in October. While the states retain the capability to exempt themselves from DST, they are forbidden by the 1966 federal law (15 USC 260a(b))[15] from increasing a state's time spent on DST, unless the United States Congress does this for the entire nation.
Starting March 11, 2007, DST was extended another four to five weeks, by moving both its start date to the second Sunday of March and its end date to the first Sunday of November. This time the change was introduced by Representatives Fred Upton and Ed Markey and added to the Energy Policy Act of 2005; the House of Representatives had originally approved a motion that would have extended DST even farther from the first Sunday in March to the last Sunday in November, but Senators Jeff Bingaman and Pete Domenici agreed to scale back the proposal in conference committee due to complaints from farmers and the airline industry. Proponents claimed that the extension would save "the equivalent of" 10,000 barrels (1,600m3) of oil per day, but this figure was based on outdated U.S. Department of Energy information from the 1970s; later studies by the U.S. Department of Energy and the California Energy Commission have predicted much smaller energy benefits.[16] There is very little recent research on what the actual positive effects, if any, might be.
Controversy
Since DST moves sunrise one hour later by the clock, late sunrise times become a problem when DST is observed either too far before the vernal equinox or too far after the autumnal equinox. Because of this, the extension was greeted with criticism by those concerned for the safety of children who would have been forced to travel to school before sunrise, especially in the month of March. In addition, the airline industry was especially concerned if DST were to be extended through to the last Sunday in November, as this is very often the Sunday after Thanksgiving (except for 2013, 2019, 2024, and 2030), as this is always the Sunday after the fourth Friday in November, and Thanksgiving is on the fourth Thursday in November. This is one of the busiest travel days at American airports, and could have resulted in much havoc among travelers who forgot that the clocks were changing that day.
If the original proposal to extend DST through the last Sunday in November had been adopted, the entire United States, with the exception of the states that exempted themselves, would have experienced the latest sunrises of the year during the month of November, which would have approached the extremely late sunrise times when DST went into effect on January 6, 1974, due to the 1973 energy crisis creeping after 9 am in places like New Salem, North Dakota at the northwestern edges of time zones.
Under the current rules, the latest sunrise occurs on the day before DST ends, everywhere in the United States that observes DST. This sunrise time is later than any during the winter months.
↑ United States statutes at large: containing the laws and concurrent resolutions enacted during the second session of the one hundred fifth congress of the United States of America 1998 and proclamations. Government Printing Office. 1999. p.599.
A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
Daylight saving time (DST), also referred to as daylight saving(s), daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the longer daylight available during summer so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in spring or late winter, and to set clocks back by one hour to standard time in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").
The Eastern Time Zone (ET) is a time zone encompassing part or all of 23 states in the eastern part of the United States, parts of eastern Canada, and the state of Quintana Roo in Mexico.
The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00). The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.
Indian Standard Time (IST), sometimes also called India Standard Time, is the time zone observed throughout the Republic of India, with a time offset of UTC+05:30. India does not observe daylight saving time or other seasonal adjustments. In military and aviation time, IST is designated E* ("Echo-Star"). It is indicated as Asia/Kolkata in the IANA time zone database.
In the United States, time is divided into nine standard time zones covering the states, territories and other US possessions, with most of the country observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation, but no single map of those existed until the agency announced intentions to make one in September 2022. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.
The Uniform Time Act of 1966, Pub. L.Tooltip Public Law 89–387, 80 Stat. 107, enacted April 13, 1966, was a Law of the United States to "promote the adoption and observance of uniform time within the standard time zones" prescribed by the Standard Time Act of 1918. Its intended effect was to simplify the official pattern of where and when daylight saving time (DST) is applied within the U.S. Prior to this law, each state had its own scheme for when DST would begin and end, and in some cases, which parts of the state should use it.
Summer time in Europe is the variation of standard clock time that is applied in most European countries in the period between spring and autumn, during which clocks are advanced by one hour from the time observed in the rest of the year, with a view to making the most efficient use of seasonal daylight. It corresponds to the notion and practice of daylight saving time (DST) to be found in some other parts of the world.
Time in New Zealand is divided by law into two standard time zones. The main islands use New Zealand Standard Time (NZST), 12 hours in advance of Coordinated Universal Time (UTC) / military M (Mike), while the outlying Chatham Islands use Chatham Standard Time (CHAST), 12 hours 45 minutes in advance of UTC / military M^ (Mike-Three).
Australia uses three main time zones: Australian Eastern Standard Time, Australian Central Standard Time and Australian Western Standard Time.
The U.S. state of Indiana is divided into Eastern and Central time zones. The official dividing line has generally moved progressively west from its original location on the Indiana–Ohio border, to a position dividing Indiana down the middle, and finally to its current location along much of the Indiana–Illinois border. This change primarily occurred to ease communications with Indiana and New York. In April 2006, several southwestern and northwestern counties reverted to Central time.
Most of the United States observes daylight saving time (DST), the practice of setting the clock forward by one hour when there is longer daylight during the day, so that evenings have more daylight and mornings have less. Exceptions include Arizona, Hawaii, and the territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Uniform Time Act of 1966 established a uniform set of rules for states opting to observe daylight saving time.
In Canada, daylight saving time (DST) is observed in nine of the country's ten provinces and two of its three territories—though with exceptions in parts of several provinces and Nunavut.
Daylight saving time in the Americas is the arrangement in the Americas by which clocks are advanced by one hour in spring and moved back in autumn, to make the most of seasonal daylight. The practice is widespread in North America, with most of Canada and the United States participating, but much less so in Central and South America.
As of 2022, daylight saving time is used in the following Asian countries:
African countries, apart from Egypt, do not use daylight saving time (DST) although some did in the past. Only the territories of the Canary Islands, Ceuta and Melilla (Spain) and Madeira (Portugal) implement DST from the last Sunday in March to the last Sunday in October. Although these regions politically belong to Europe, they are geographically part of Africa. They have DST schedules according to European Union rules.
Parts of Australia, New Zealand and Fiji are areas of Oceania that currently observe daylight saving time (DST).
Portugal has two time zones and observes daylight saving time. Continental Portugal and Madeira use UTC+00:00, while the Azores use UTC–01:00. Daylight saving time is observed nationwide from the last Sunday in March to the last Sunday in October, when continental Portugal and Madeira advance one hour to UTC+01:00, and the Azores advances one hour to UTC+00:00.
Daylight saving time (DST), also known as summer time, is the practice of advancing clocks during part of the year, typically by one hour around spring and summer, so that daylight ends at a later time of the day. As of 2024, DST is observed in most of Europe, most of North America and parts of Africa and Asia around the Northern Hemisphere summer, and in parts of South America and Oceania around the Southern Hemisphere summer. It was also formerly observed in other areas.
Establishing either permanent standard or daylight saving time (DST) eliminates the practice of semi-annual clock changes, specifically the advancement of clocks by one hour from standard time to DST on the second Sunday in March and the retraction of clocks by one hour from DST to standard time on the first Sunday in November.
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