DST history by country

Three eras explain most of these timelines

Wartime economics started the practice. Port Arthur, Ontario is cited as the first known place to run modern DST in 1908, and Germany introduced the first nationwide period on April 30, 1916, with the United Kingdom, France, Italy, and Belgium following the same year. The aim was fuel saving rather than convenience, which is why many countries dropped their clock changes as soon as each war ended.

The 1970s energy crisis brought seasonal time back. France resumed it in 1976, the Netherlands in 1977, and New Zealand reintroduced clock changes after a 1974 to 1975 trial. Europe later harmonized on the last Sunday in March to last Sunday in October pattern, and the United States settled on its current second Sunday in March to first Sunday in November season in 2007.

The recent movement runs the opposite way. Argentina stopped in 2009, Russia ended seasonal switching in 2011 and chose permanent standard time in 2014, Turkiye stayed on UTC+3 from 2016, Morocco fixed UTC+1 in 2018, Brazil abolished DST in 2019, and Iran and Mexico followed in 2022. Egypt went against the tide and reintroduced clock changes in April 2023 after eight years without them.

Reading the event labels

Every entry on a country page carries a year, one of four actions, and at least one source. Adopted marks a first observance or a return after a long gap. Abolished marks the end of seasonal changes. Modified covers schedule shifts, regional exceptions such as Chile's Magallanes Region moving to a fixed UTC-03:00 in 2017, and permanent-offset experiments. Voted-on flags reforms that passed a vote without becoming law, the 2019 European Parliament decision being the standing example.

Why old clock rules still matter

Any timestamp recorded under a rule listed here, server logs, medical records, financial trades, birth certificates, needs the offset that was in force at that moment to convert correctly. The IANA time zone database encodes transitions from 1970 onward for every zone, which is why software usually handles recent history well. Dates before 1970, or inside short-lived arrangements like Russia's 2011 to 2014 permanent summer time or Cuba's 2004 to 2006 year-round DST, are exactly where a sourced timeline earns its keep.

Questions about DST history