Daylight saving time in the Americas

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, Mexico, and the United States of America participating, but much less so in South America.
North America.
Canada, Mexico, and the United States of America.
Canada, Mexico, and the United States of America use daylight saving time on a wide scale, with only a few states/provinces and parts thereof opting out of the practice or adopting it year-round without the twice yearly switch.
The United States territory of Puerto Rico remains in Atlantic Standard Time (AST) all year long.
Since 2007, in areas of Canada and the United States of America in which it is used, daylight saving time begins on the second Sunday of March and ends on the first Sunday of November. In Mexico, Congress has consistently been refusing to adopt this schedule on a nationwide basis, so only certain border cities in Mexican states that observe DST follow the same pattern as Canada and the United States of America. The rest of Mexico remains out of phase beginning DST on the first Sunday of April and ending on the last Sunday of October, the same schedule followed by Canada and the United States of America prior to 2007.
Saint Pierre and Miquelon.
Saint Pierre and Miquelon, located near the Canadian coast, belongs to France, but observes daylight saving time according to Canadian rules.
Greenland.
Greenland (excluding two minor areas at Danmarkshavn and Pituffik) observes DST and uses the European convention (DST begins 01:00 UTC last Sunday in March and ends 01:00 UTC last Sunday in October). Most populated places in the country are in the zone in the winter ( in the summer). Because of this, with respect to local time, clocks are changed from 22:00 to 23:00 in the spring (on the Saturday before the last Sunday in March), and reset back from 23:00 to 22:00 in the autumn (on the Saturday before the last Sunday in October).
Danmarkshavn does not use DST, because it is a weather station with an airstrip which is supplied from Iceland, which does not use DST. This might apply to some other weather stations in the area.
Pituffik/Thule Air Base uses and United States conventions on DST because it is a US air base, meaning it is part of the Atlantic Time Zone.
Bermuda.
Bermuda has observed DST annually since 1974.
The Caribbean lands.
Puerto Rico remains all year long in Atlantic Standard Time. (AST). 
The Bahamas.
The Commonwealth of The Bahamas observes DST according to the American schedule.
Barbados.
Barbados in the western Atlantic no longer observes Daylight Saving Time, like many Caribbean nations. The last observance of a daylight saving-related time clock adjustment was between Sunday, 20 April 1980 at 2:00 AM – Thursday, 25 September 1980 at 2:00 AM. On 25 September the clock was shifted -3:00 – -4:00 where it has remained since.
Cuba.
Cuba normally observes DST from March to October although the precise dates vary. For two years in the mid-2000s (decade), Cuba stayed on DST throughout the year. In 2009 it was on DST from the second Sunday in March to the last Sunday of October. In 2011, it was on DST from the third Sunday in March to the second Sunday in November.
Dominica.
Dominica in the Caribbean does not observe Daylight Saving Time, like several other Caribbean nations.
The Dutch Caribbean Islands.
The Dutch Caribbean islands of Aruba, Bonaire, Curaçao, Saba, Sint Eustatius and Sint Maarten do not observe Daylight Saving Time.
The French Caribbean Islands.
The French Caribbean islands of Guadeloupe, Martinique, Saint-Barthélemy and Saint-Martin do not observe Daylight Saving Time. 
Haiti.
Haiti had reestablished Daylight Saving Time in 2012, following the US/Canada DST Rules, starting on the second Sunday in March and ending on the first Sunday in November. This was discontinued in 2016,but was re-introduced in 2017.
Jamaica.
Jamaica previously used Daylight Saving Time, utilising the US and Canadian rules. The practise was used from 1974 before being discontinued in 1983.
Trinidad and Tobago.
Trinidad and Tobago remains on Atlantic Standard Time and does not observe DST.
The Turks and Caicos Islands.
Turks and Caicos discontinued Daylight Saving Time in March 2015, at the same time moving from the Eastern Time Zone to the Atlantic Time Zone, the end result being the same as having year-round Daylight Saving in the Eastern Time Zone.
In 2018, the islands reintroduced daylight saving time by setting the clocks back 1 hour to Eastern Standard Time; the islands follow the same daylight saving schedule as the United States of America and Canada.
Central America.
Guatemala.
Guatemala has used DST during energy crises. The last time it used DST was from April 30, 2006, to October 1, 2006.
Honduras.
Honduras adopted DST from May 1994 until September 1994 but then abandoned it. On May 7, 2006 it again used DST; however it ended on August 7, 2006, making this the shortest use of DST in the northern hemisphere as it was only applied for 3 months. The government decided not to use DST in 2007.
Nicaragua.
Nicaragua observed DST from January 1, 1992 until February 20, 1994 but it was stopped. On April 10, 2005 until October 2, 2005 DST was implemented, and the following year the period was similar, beginning on April 30, 2006 and ending on October 1, 2006; this measure was for energy conservation. In 2007, the government of Nicaragua decided to stop observing daylight saving time.
South America.
In equatorial regions, DST is not useful because of the stability of light levels throughout the year. As a result large areas of South America do not observe DST. DST is used in some of the more southerly countries such as Paraguay and most of Chile.
These countries or regions in South America do not use daylight saving time:
Argentina.
Since 2009, Argentina has not been observing DST and the entire country has stayed on . Argentina is located at a longitude that would naturally put it in the UTC−04:00 or UTC−05:00 time zone.
San Luis province, which was previously in a different time zone than most of the country and which formerly observed DST, decided in April 2010 not to change its clocks back and to stay on all year round.
The most recent history of Argentina observing DST dates from 2007 to 2009. After a period of not observing DST, Argentina observed DST in some provinces in an attempt to save energy. For each period, the executive branch of the government set the specific start and end dates for DST, i.e. there was no fixed annual schedule.
Bolivia.
In 2011, Bolivia planned to observe DST starting September 1 for the first time in its history, advancing the clock an hour on a nationwide basis in order to offset their energy problems. The schedule change was planned to take place every year between September and March, corresponding to the spring and summer of the South American country. However, the day before the scheduled change, on August 31, 2011, the national government indefinitely suspended the observation of DST due to opposition from experts in electricity, neighborhood and school leaders, and the general populace.
Brazil.
Brazil adopted DST (called "horário de verão"—"summer time"—in Portuguese) for the first time in 1931, and it was in effect across the entire country. The duration and regional applicability of DST has varied over the years (see for details). As of 2013, DST was used only in the southern region (the states of Rio Grande do Sul, Santa Catarina, Paraná), the southeast region (the states of São Paulo, Rio de Janeiro, Espirito Santo, Minas Gerais), and the central-west region (the state of Goiás and the Distrito Federal, and the states of Mato Grosso and Mato Grosso do Sul).
Formerly, starting and ending dates were variable, but in 2008, a decree (No. 6558 of 9 September 2008) established a permanent rule: DST starts at 00:00 on the third Sunday in October from 2008 to 2017 (and on the first Sunday in November from 2018 to the present), and ends at 00:00 on the third Sunday in February—unless the latter falls during Carnaval: in this case, the end of DST was postponed by one week.
In 2019, Brazil scrapped daylight saving time and now stays on standard time year round.
Chile.
Chile currently observes DST from the first Saturday in September to the first Saturday in April.
In the past, DST was observed from the second Saturday in October to the second Saturday in March, but it has varied (see Time in Chile). In 2008, for example, the time was adjusted on Sunday, March 30, at 12 midnight.
In 2010, because of an earthquake, DST remained in effect until April 3. 
In 2011, in order to prevent energy shortages after a dry summer, DST was first extended until April 2 and then until May 7.
From 2011-2014, Chile DST started the first Saturday of September at 24:00, and ended the last Saturday of April at 24:00.
DST was not observed in 2015 when the government declared that the country would remain on permanently. But on March 16, 2016, decree 253 modified the 2015 decision and restored winter time. It would last 90 days from the second weekend of May to the second weekend of August.
Colombia.
From February 1992 until March 1993, Colombia suffered rolling blackouts of up to 10 hours a day due to a particularly strong El Niño season, which dried the reservoirs in hydroelectric plants in a country deriving 70% of its energy output from hydroelectric sources; consequently, the government decided to use DST to help save electricity. The experiment failed to deliver the intended results, possibly due to Colombia's low latitude, and the DST experiment was discontinued.
Ecuador.
Ecuador's President Sixto Durán Ballén imposed daylight saving time in 1992 in an energy-saving effort. It was poorly received by the populace and did not last long.
Falkland Islands.
DST () is generally observed from the first Sunday of September to the third Sunday of April. However, the Falklands remained on DST throughout 2011 and 2012.
Paraguay.
Paraguay observes DST under decree 1867 of March 5, 2004. DST ends on the second Sunday of March and starts on the third Sunday of October.
In 2007, DST started on October 15, 2006 and ended on March 11, 2007.
In 2010, Paraguay changed its own DST rules because of the energy crisis, ending DST on the second Sunday in April, a month later than previous years. The start date remains unchanged.
Uruguay.
Since 2004, Uruguay has observed DST. Starting in 2006, DST begins on the first Sunday in October and ends on the second Sunday in March of every year. On 30 June 2015, Uruguay abolished DST.