Daylight Saving Time in the United States Explained

Daylight Saving Time (DST)

In the United States, Daylight Saving Time begins on the second Sunday of March and ends on the first Sunday of November. Both switches happen at 2:00 AM local time, which means the country does not change its clocks all at once — the shift rolls westward zone by zone. Two states and every inhabited US territory sit the whole thing out.

Key takeaways

Clocks spring forward at 2:00 AM on the second Sunday of March and fall back at 2:00 AM on the first Sunday of November.
DST covers 238 days — about 65% of the year, not half of it.
Arizona (except the Navajo Nation) and Hawaii do not observe it, nor do Puerto Rico, the US Virgin Islands, Guam, American Samoa or the Northern Mariana Islands.
The rules come from the Uniform Time Act of 1966; the current dates were set by the Energy Policy Act of 2005, effective 2007.
A state may opt out of DST on its own, but adopting permanent DST requires an act of Congress.

When Does Daylight Saving Time Start and End?

The dates are defined by rule rather than by fixed calendar days, so they move a little each year. Since 2007 the pattern has been the same: the second Sunday of March through the first Sunday of November.

Year	DST begins (clocks forward)	DST ends (clocks back)
2026	Sunday, 8 March	Sunday, 1 November
2027	Sunday, 14 March	Sunday, 7 November
2028	Sunday, 12 March	Sunday, 5 November

The gap between the two dates is always exactly 34 weeks, or 238 days. That is worth remembering, because the common assumption that the country spends half the year on standard time and half on daylight time is wrong: standard time now covers barely four months.

What Actually Happens at 2:00 AM

Both transitions are written into law as happening at 2:00 AM local time, which produces two small oddities on the clock.

In March, an hour disappears

At 2:00:00 AM the clock jumps straight to 3:00:00 AM. The hour from 2:00 to 2:59 AM never happens that day, so a Sunday in March is only 23 hours long. Anyone born at 2:30 AM has no birthday minute that morning, and software that assumes every day has 24 hours tends to misbehave.

In November, an hour repeats

At 2:00:00 AM the clock falls back to 1:00:00 AM, so the hour from 1:00 to 1:59 AM occurs twice — once on daylight time and once on standard time. That Sunday is 25 hours long, and a timestamp like “1:30 AM” is genuinely ambiguous unless you also state the offset.

Because the rule is tied to local time, the switch happens in a westward wave rather than simultaneously. New York changes its clocks a full three hours before Los Angeles does, and Alaska changes an hour after that. For roughly five hours each transition morning, the usual offsets between US cities do not hold.

How Each US Time Zone Shifts

Every zone that observes DST moves one hour closer to UTC, and its abbreviation changes from Standard to Daylight — EST becomes EDT, PST becomes PDT, and so on.

Zone	Standard time	Daylight time	Observes DST?
Eastern	EST, UTC−05:00	EDT, UTC−04:00	Yes
Central	CST, UTC−06:00	CDT, UTC−05:00	Yes
Mountain	MST, UTC−07:00	MDT, UTC−06:00	Yes, except most of Arizona
Pacific	PST, UTC−08:00	PDT, UTC−07:00	Yes
Alaska	AKST, UTC−09:00	AKDT, UTC−08:00	Yes
Hawaii–Aleutian	HST, UTC−10:00	HDT, UTC−09:00	Only the western Aleutians, not Hawaii

Note that Hawaii–Aleutian is a single zone whose two halves behave differently: the Aleutian Islands west of about 169°30′W do observe DST, while the state of Hawaii does not. If you are unsure which abbreviation applies on a given date, our guide to time zone abbreviations explains why writing “EST” in July is almost always a mistake. For the full geography of the zones, see Time Zones in the United States Explained.

Which States and Territories Skip It?

Federal law lets any state exempt itself from Daylight Saving Time by keeping standard time all year. Two have done so, along with every inhabited territory:

Arizona — on Mountain Standard Time year round since 1968. In practice this means Phoenix matches Denver in winter and Los Angeles in summer. The state tried DST in 1967, found that an extra hour of evening sun in a desert summer was no gift at all, and opted out the following year.
Hawaii — out since 1967. Sitting close to the tropics, Honolulu sees only about 90 minutes of variation in day length between June and December, so shifting the clock buys nothing.
Puerto Rico, the US Virgin Islands, Guam, American Samoa and the Northern Mariana Islands — all remain on standard time year round, for the same reason: they are close enough to the equator that summer evenings do not stretch.

There is a well-known exception inside the Arizona exception. The Navajo Nation, whose territory spans Arizona, Utah and New Mexico, does observe DST so that its own lands keep one consistent clock across three states. The Hopi Reservation, which is surrounded entirely by the Navajo Nation, does not — producing a small patch of northeastern Arizona where the local time can change several times over a short drive. Arizona and Hawaii are far from alone globally; see Countries That Do Not Use Daylight Saving Time for the wider picture.

The Law Behind the Rules

American clock changing has been switched on, off and rewritten more often than most people realise:

Year	What changed
1883	The railroads impose four standard zones on the “Day of Two Noons”, thirty-five years before any federal law.
1918	The Standard Time Act introduces both federal time zones and a wartime DST. DST is repealed a year later over farmers’ objections.
1942–1945	Year-round “War Time” during the Second World War.
1945–1966	No federal rule at all. Cities and states choose their own dates, producing a patchwork that broadcasters and bus companies openly called chaos.
1966	The Uniform Time Act sets national start and end dates, while allowing any state to opt out entirely.
1974	An oil-crisis experiment puts the country on year-round DST. Dark winter school mornings make it deeply unpopular and it is repealed within the year.
1986	DST moves to the first Sunday of April.
2005	The Energy Policy Act extends DST by about four weeks, to the current March–November window, effective from 2007.

The two-decade gap without a federal standard is the reason the Uniform Time Act exists. In the mid-1960s a 35-mile bus route between Steubenville, Ohio and Moundsville, West Virginia crossed seven different local time regimes, and Minneapolis and St. Paul — twin cities sharing a river — spent part of one summer an hour apart. Uniformity, not energy, was the original argument.

It is a pattern that repeats throughout the story of American time: the railroads standardised the clock in 1883 because nobody else would, and Washington ratified the result decades later. That whole arc, from local solar noon to a global grid, is traced in The History of Time Zones: From Local Noon to Standard Time.

Will the United States Stop Changing the Clocks?

It is a recurring proposal, and in 2026 it came closer than ever. The Sunshine Protection Act, which would make daylight time permanent nationwide, passed the US Senate by unanimous consent in March 2022 but was never taken up by the House. A later version passed the House by 308 votes to 117 on 14 July 2026 and now awaits the Senate. Nothing has changed in law yet. Around twenty states have passed their own legislation declaring that they would adopt permanent DST — but every one of those laws is conditional, because of an asymmetry in the Uniform Time Act:

A state may exempt itself from DST and stay on standard time forever. Arizona and Hawaii did exactly that, and no federal permission was needed.
A state may not stay on daylight time forever. That requires Congress to amend the federal statute first.

So the state-level bills are effectively waiting in a queue for a federal decision that has not arrived. Note also that the two options are not the same thing: permanent standard time favours earlier sunrises, permanent daylight time favours later sunsets, and the 1974 experiment suggests the public reacts badly to dark winter mornings. Sleep researchers and many medical associations tend to favour permanent standard time; retail and leisure industries have historically favoured the opposite. The full legislative picture, including the parallel European debate and the countries that have already stopped, is in Will Daylight Saving Time Be Abolished?

Practical Notes for Scheduling

Two details cause most of the real-world confusion. First, the US and Europe do not switch on the same weekends — America moves in early March while the EU and UK wait until the end of the month, so transatlantic offsets are temporarily one hour off for about three weeks each spring and one week each autumn. Our guide to clock change dates around the world lists the exact weekends.

Second, purely domestic US pairs are unaffected, because every observing state switches on the same date at the same local hour. The gap between the coasts stays at three hours all year, which is what makes New York and Los Angeles one of the easiest long-distance pairs to plan around. Canada uses identical dates, so cross-border offsets are equally stable (Time Zones in Canada Explained).

The hardest cases are partners who never change at all. India keeps UTC+5:30 year-round, so an American clock change moves the meeting for the Indian side rather than the American one — a recurring source of missed calls covered in Best Time for Meetings Between the USA and India.

Frequently Asked Questions

What time do the clocks change in the United States?

At 2:00 AM local time on both dates. In March the clock jumps forward to 3:00 AM; in November it falls back to 1:00 AM. Because the rule uses local time, the change sweeps across the country from east to west rather than happening everywhere at once.

Which US states do not observe Daylight Saving Time?

Arizona and Hawaii. Within Arizona, the Navajo Nation does observe DST, while the Hopi Reservation inside it does not. Puerto Rico, the US Virgin Islands, Guam, American Samoa and the Northern Mariana Islands also stay on standard time all year.

Why does Arizona not change its clocks?

Arizona observed DST in 1967 and opted out in 1968. In a desert climate, an extra hour of evening daylight in summer means an extra hour of extreme heat and air-conditioning demand, so the usual argument for DST works in reverse there.

How long does DST last in the USA?

Exactly 34 weeks, or 238 days — roughly 65% of the year. Standard time now covers only about four months, from early November to early March.

Can a state make Daylight Saving Time permanent on its own?

No. Under the Uniform Time Act a state can leave DST and remain on standard time without asking anyone, but adopting permanent daylight time requires Congress to change federal law first. That is why the roughly twenty state laws on the books are all written to take effect only once federal law allows it.