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Daylight Saving Time in the USA

The US is one of about 70 countries worldwide using Daylight Saving Time (DST), but Hawaii and most of Arizona don't use it.

Illustration image

Most of Arizona, including its capital, Phoenix, does not use DST.

©iStockphoto.com/Dreamframer

When Does DST Start and End?

DST in the United States begins each year on the second Sunday in March, when clocks are set forward by one hour. They are turned back again to standard time on the first Sunday in November as DST ends.

Not All States Use DST

Almost all of the US states have yearly clock changes. The only exceptions are Hawaii and Arizona.

Hawaii observes Hawaii Standard Time (HST) all year.

Most of Arizona observes Mountain Standard Time (MST) year-round, except the Navajo Nation, because its territory extends into Utah and New Mexico—both states that observe DST.

Indiana decided to join the national DST regime in 2006 after abstaining from changing its clocks since 1970.

None of the US dependencies use DST, including American Samoa, Guam, Puerto Rico, the Northern Marina Islands, the US Minor Outlying Islands, and the US Virgin Islands.

Some States Want to Remove DST

According to the National Conference of State Legislatures, 19 states have enacted legislation or passed regulations for permanent DST.

Note: For the bills to become law, the US Congress must first pass a federal law that would allow states to observe DST year-round. This has not happened yet. The current law only allows states to opt out of DST, but not to follow it year-round.

StateYearLawGoalCongress*
Mississippi2021House Bill 1062Permanent DST
Georgia2021Senate Bill 100Permanent DST
Montana2021Senate Bill 254Permanent DST
Alabama2021Senate Bill 388Permanent DST
Minnesota2021Chapter 12 amendmentPermanent DST
Utah2020Senate Bill 59Permanent DST
South Carolina2020Act No. 113Permanent DST
Georgia2020House Resolution 1240Permanent DST
Idaho2020Senate Bill 1267Permanent DST
Wyoming2020House Bill 0044Permanent DST
Louisiana2020House Bill 132Permanent DST
Delaware2019Senate Bill 73Permanent DST
Maine2019Legislative Document 885Permanent DST
Oregon2019Senate Bill 320Permanent DST
Washington2019House Bill 1196Permanent DST
Tennessee2019Senate Bill 1100Permanent DST
Arkansas2019House Resolution 1034Permanent DST
Florida2018Sunshine Protection ActPermanent DST
California2018Proposition 7Permanent DST

*Congressional approval needs to be in place for the state law to take effect.

DST Starts at 2 am Local Time

By law, all clock changes in the US occur at 02:00 (2 am), in each state's local time. In spring, clocks are set forward to 03:00 (3 am); they are turned backward to 01:00 (1 am) in the fall.

However, since the US spans several time zones, the clock changes, while occurring at the same local time in each time zone, do not happen simultaneously. Eastern time zones switch earlier than western time zones. For example, each DST change happens three hours earlier in New York than in Los Angeles.

In Europe, it's the other way around: The continent begins and ends its DST periods at 01:00 UTC, resulting in a simultaneous DST change across Europe—but at different local times.

History: When Did DST Start in the USA?

In 1916, during World War I, Germany became the first country to adopt DST to save energy for the war effort. Many countries across Europe soon followed suit. In the US, “Fast Time,” as it was called then, was first introduced in 1918. The initiative was sparked by Robert Garland, a Pittsburgh industrialist who had encountered the idea in the United Kingdom.

Only seven months later, DST was repealed. But some cities, including Pittsburgh, Boston, and New York, continued to use it.

“War Time” and “Peace Time”

In 1942, at the height of World War II, President Franklin D. Roosevelt reintroduced the measure, instituting year-round Daylight Saving Time in the US. Referred to as “War Time,” DST was in force continuously from February 9, 1942 to September 30, 1945.

During this time, the US time zones were called “Eastern War Time,” “Mountain War Time,” “Central War Time,” and “Pacific War Time.” After the surrender of Japan in mid-August 1945, the time zones were relabeled “Peace Time.”

National DST Rules since 1966

From 1945 to 1966, there were no uniform rules for DST in the US. This caused widespread confusion, especially for trains, buses, and the broadcasting industry. As a result, the Uniform Time Act of 1966 was established. While granting US states the ability to opt out of DST, the law provided a framework for a nation-wide, synchronized DST schedule, starting on the last Sunday of April and ending on the last Sunday of October.

Year-Round DST in 1973

During the 1973 oil embargo, the US Congress ordered a year-round DST period lasting from January 1974 to April 1975. The rationale was to study the effects of seasonal time change on energy consumption. Following staunch opposition from the public and the realization that the measure yielded only modest energy savings, the plan was soon amended to allow for a return to standard time during the winter months.

Energy Policy Act of 2005

After the energy crisis was over in 1976, the United States DST schedule was revised several times throughout the years. From 1987 to 2006, the country observed DST for about seven months each year. The current schedule was introduced by the Energy Policy Act of 2005 and has been followed since 2007.

Topics: Daylight Saving Time, History, Time Zone