Twice every year, most Americans change their clocks. Along with most European states, parts of Australia, and a handful of other countries around the world, 48 out of the 50 US states ‘spring forward’ an hour on the second Sunday in March, and ‘fall back’ an hour on the first Sunday in November.1 The result is that the four time zones of the contiguous United States (Eastern, Central, Mountain and Pacific) spend almost two-thirds of the year on daylight saving time (DST) instead of on standard time, with only the winter months exempted.2 During DST periods, the sun rises and sets later according to clocks, resulting in darker mornings but longer, brighter evenings.

The current DST system of biannual clock changes is highly unpopular in the United States.3 It is perennially blamed for an increase in deaths, stress levels, seasonal depression, and economic costs in excess of US$400 million due to the confusion associated with the time changes.4 However, there is no consensus among US lawmakers or civil society on whether to abolish the present DST system in favour of permanent standard time, or to create permanent year-round DST, extending the dark mornings and bright evenings into winter as well as summer.5 Under permanent (ie year-round) DST, DST would be in place year-round and clocks would be put forward one hour and never be put back, permanently advancing each time zone by one hour. Under a permanent standard time system, DST would not exist and clocks would not be put forward in summer.

In March 2022, the US Senate controversially passed the Sunshine Protection Act of 2021 by unanimous consent, which would have implemented nationwide permanent DST.6 However, the legislation lapsed in the House of Representatives with the end of the 117th Congress in January 2023.7 The Sunshine Protection Act of 2023 is now being considered by both the House and Senate.8

The politics of daylight saving time give insight into how millions of Americans live their daily lives, but also highlight a rare instance of legislation dividing on geographic, rather than partisan, lines.

Until the act’s unexpected passage in 2022, DST proposals in recent years had garnered little public interest or political attention. Many Senators were blindsided by the passage of the bill and were not even in attendance at the March 2022 Senate session.9 Mass media attention, public scrutiny and legislative backlash came only after the passage of the act. The politics of DST give insight into how millions of Americans live their daily lives, but also highlight a rare instance of legislation dividing on geographic, rather than partisan, lines. As would have occurred had the Sunshine Protection Actof 2021 become law, lack of due consideration by Congress can result in poorly understood and seemingly inconsequential changes to legislation having sweeping impacts on the lives of hundreds of millions of Americans.

Polling indicates that the American public is fragmented and noncommittal on the appropriate solution to DST issues. According to an October 2023 YouGov poll, 68 per cent of Americans want to abolish clock changes, and just 17 per cent of Americans support the current system.10 However, 33 per cent support year-round permanent DST, 23 per cent support permanent standard time, and a further 26 per cent are undecided.

While DST in summer unquestionably offers benefits for some areas of the United States at certain times, these benefits are unevenly distributed. Due to the negative impacts year-round permanent DST would have on a significant proportion of the US population in winter and the ongoing unpopularity and confusion surrounding the present system of time changes, this brief recommends rejection of the Sunshine Protection Act and amendment of the Uniform Time Act of 1966 to abolish DST in favour of permanent standard time.

US daylight saving time: the basics

DST observance in the United States is governed by the federal Uniform Time Act of 1966, which regulates US time zones and the timing and management of DST.11 States may choose to opt-out of DST observance, in which case they must observe permanent standard time.12 Federal law does not permit a state to observe permanent DST. Among the 48 contiguous US states, only Arizona currently observes permanent standard time, having opted-out of DST observance in 1968 due to the state’s hot weather making longer daylight hours in summer afternoons undesirable.13

Unusually for a US policy debate, political disagreements over DST do not fall on party lines but instead conform to geographic realities.14 Driven by dissatisfaction with the current system, 19 states have passed legislation or resolutions in the last five years that would provide for permanent DST if permitted by Congress, including Colorado, Georgia, South Carolina and Washington.15 In 2023, 29 US states considered DST-related legislation.16 Other states have commissioned studies to consider the possibility of observing permanent standard time.17

The diversity of state-based approaches is reflective of the public indecision on the issue and relative lack of serious attention it has received.

Option DST status Impact on time zones Impact on days
Status quo
(Uniform Time Act of 1966)
DST in effect between March and November, Standard Time in effect in winter

All US time zones advance by one hour between March and November relative to their current standard time, and regress to standard time in winter Later sunrises and sunsets in summer, spring, and autumn; earlier sunrises and sunsets in winter
Permanent DST
(Sunshine Protection Act)
DST in effect year-round All US time zones permanently advance by one hour relative to their current standard time Later sunrises and sunsets year-round; more sunlight in evenings, less sunlight in mornings
Permanent Standard Time DST abolished All US time zones stay on standard time year-round
Earlier sunrises and sunsets year-round; more sunlight in mornings, less sunlight in evenings

US time changes over time

DST has a long and controversial history in the United States. It was first introduced in the United States during the First World War as an energy saving measure as part of the Calder Act in 1918 which formalised standard US time zones.18 American founding father Benjamin Franklin is often erroneously credited with the invention of DST, though he did propose the shifting of waking hours in jest in 1784.19

President Woodrow Wilson vetoed a 1919 repeal of DST, arguing that the benefit of DST for urban factory workers who benefited from later sunlight hours outweighed the impacts on farmers who objected to the darker mornings it caused.20 In an acrimonious debate on the override of the veto, Congressman Thomas Blanton decried supporters of DST as “night wasters.”21 Wilson’s veto was one of just six which were overridden by Congress during Wilson’s time in office, by a vote of 223–101 in the House and 57–19 in the Senate.22 DST would later be reintroduced year-round as ‘War Time’ for a period during the Second World War, again as an energy saving measure.23

The passage of the Uniform Time Act of 1966 was motivated by frustration with inconsistent and unregulated observance of DST, with different states and localities determining whether they put their clocks forward, and for how long.24 The act implemented a national framework for DST observance, with a common period of DST use and a general requirement that states participate or exempt themselves from DST observance as a whole, rather than permitting county-level changes.25

United Cigar Stores Company daylight saving time promotional poster, ca.1917.Source: Getty

In 1973, Congress authorised a two-year trial of year-round permanent DST as an energy-saving response to the 1973 global oil crisis.26 While public approval for the trial initially stood at almost 80 per cent, this support had almost halved by the end of the 1973–74 winter.27 Safety concerns for children, particularly regarding road accidents after the deaths of eight children in Florida, were a significant cause of the collapse in support.28 The construction industry also opposed the trial due to the heightened risks of working in darker winter mornings. However, the empirical effects of the experiment, both positive and negative, were largely ambiguous.29

Congress aborted the permanent DST experiment before the following winter.30 The episode highlighted the brittleness of public support for poorly-understood policy options — an infamous issue with DST despite its ubiquity and impact on the lives of almost all Americans.31 The United States has since maintained its twice-yearly time changes since the end of the national permanent DST experiment.32 However, the period in which DST is observed has twice been extended to now encompass an eight-month period between March and November, with Standard Time in operation only during the northern hemisphere winter.

The Sunshine Protection Act

In March 2022, the US Senate controversially passed by unanimous consent the Sunshine Protection Act of 2021, introduced by Senator Marco Rubio (R-FL), which would have implemented nationwide permanent DST.33 Rubio has repeatedly introduced the bill since 2018, but previously failed to gain traction. Despite the legislation having support from across the political aisle, numerous Senators said they did not have a chance to review the bill before its passage and some would have objected to the voice vote had they known it was taking place.34 Nevertheless, the legislation lapsed in the House of Representatives with the end of the 117th Congress.35

"This ritual of changing time twice a year is stupid. Locking the clock has overwhelming bipartisan and popular support." — Senator Marco Rubio, 2 March 202336

In March 2023, the Sunshine Protection Act of 2023 was introduced in both the House and the Senate and has been referred to the House Subcommittee on Innovation, Data and Commerce, and the Senate Committee on Commerce, Science, and Transportation where it is awaiting further action.37 Given that the acts of 2018, 2019 and 2021 all died in committee, it may be that there is little further movement in the 118th Congress. Nevertheless, since the 2022 vote, the bill has attracted significant media coverage and public attention. Urban business interests in particular have long supported moves to extend and implement DST.38 Industry groups such as the Association For Convenience & Fuel Retailing (NACS) and the US Chamber of Commerce have supported extensions to DST observance due to its economic benefits and the increased leisure time it provides urban workers to pursue activities in brighter evenings, while other proponents have highlighted benefits to public safety and possible energy savings.39 Sleep scientists and physicians have led opposition to the bill,40 arguing the dark mornings in which it would result would be detrimental to public health.41

Senator Edward Markey (D-MA), dubbed the ‘Sun King’ for his role in passing previous DST legislation, speaks in favour of permanent DST, 15 March 2022 (C-SPAN)Source: Creative commons

The problem with permanent DST

The primary issue with permanent DST is the late mornings it creates in winter. In summer, DST results in late sunset times and sunrises between 5am and 6am in most of the United States.42 However, seasonal variation in the lengths of days throughout the year means that, if permanent DST were implemented, huge swathes of the country would see exceptionally late sunrises in winter that are currently almost unheard of in the United States.

Analysis of the population distribution of the United States reveals the impact this change would have on the 80 per cent of the US population which lives in urban areas. Under permanent DST, 87 per cent of the urban population of the United States would experience sunrise after 8am in winter, compared with just three per cent of the urban population which currently experiences such late sunrises. On the winter solstice — the shortest day of the year — cities including New York, Chicago, San Francisco, Philadelphia, Washington DC, Denver and Tampa would all see sunrise occurring after 8.15am.43 In early January, the sun would rise even later in each location depending on their latitude.

Additionally, 44 per cent of the 2,585 urban areas in the contiguous United States, over a quarter of the urban US population, would experience sunrise after 8.30am.44 By contrast, the largest city to currently see such a late sunrise under the existing DST regime is Boise, Idaho, which currently experiences sunrise at 8.15am at the latest, and which would see winter sunrises at 9.15am if permanent DST were implemented.45

The relative benefits of winter DST would also be limited, with sunset times being no later than 6.30pm in the vast majority of the country at the winter solstice.46

For US workers, 58.8 per cent of whom leave for work prior to 8am, and 26 per cent of whom leave between 7am and 8am, a change to permanent DST would result in wakeup times well before sunrise and winter commutes largely undertaken in darkness.47 Journeys to school for many children would begin in darkness in winter, with the current average school start time around 8am prior to sunrise for an overwhelming majority of the population.48 The 1974–75 permanent DST experiment was largely derailed by these impacts. Increased urbanisation in the last 50 years would likely heighten their effect.49

Sleep scientists are overwhelming opposed to DST, and particularly to permanent DST, due to the desynchronisation it creates between civil time (ie clock time) and natural human circadian rhythms.50 The shift to DST has been associated with increased rates of cardiovascular events, stroke, hospital admission, stress, lack of sleep and vehicular accidents.51 Imposition of such a large disparity in winter between solar time and civil time on a population level is likely to cause a noticeable impact on public health through “social jet lag” and the impacts listed above.52 The Sunshine Protection Act has faced formal opposition from the American Academy of Sleep Medicine on these grounds.53 By contrast, business associations and the US Chamber of Commerce have supported moves to extend DST, with proponents arguing that it benefits businesses and public safety, and reduces energy consumption due to reduced evenings darkness.54 There is mixed evidence to support these claims.55 Nevertheless, regardless of the benefits of the current DST system, the fact that winter sunsets would still occur so early even with permanent DST suggests that the relative benefits of such a change would not outweigh the negative consequences of nation-wide dark mornings.

The fact that winter sunsets would still occur so early even with permanent DST suggests that the relative benefits of such a change would not outweigh the negative consequences.

The purpose of time zones and their enforceable oversight by the Department of Transport is to create standards of time that remains roughly reflective of solar time in as wide an area as possible.56 Permanent standard time is the most effective means of doing so because the impacts on the lives of individuals can be mediated through more adaptable means than wholesale artificial changes to time systems. In winter, when such changes would have adverse effects, social standards are likely to gradually adapt to the change, negating the use of permanent DST in the first place. In response to the 1974–75 experiment, schools in at least 18 states began adjusting their starting hours, sparing children from dark mornings but, in effect, reverting to the previous standard time system.57

Over time under a permanent DST system, the United States would likely see broad adjustment of social hours that ultimately only puts the population further out of step with official civil time. If urban workplaces gradually moved to regular winter working hours of 10am–6pm DST to spare their workers from dark commutes, this would, in practice, leave the same number of evening daylight hours as currently exist. The result would be little adjustment to Americans’ ways of living in the long term beyond further misalignment of official civil time with solar time.

The permanent standard time alternative

In contrast to permanent DST, some sleep scientists instead advocate for the abolition of time changes by implementing permanent standard time.58 Permanent standard time would see earlier sunrises and sunsets than under permanent DST, with all US time zones staying on ‘winter time’ year-round. Almost a dozen US states are currently considering permanent standard time legislation.59

As with permanent DST, permanent standard time would bring with it the benefits of eliminating costly and stressful biannual clock changes. However, it would more closely align civil (ie clock) time and natural human circadian rhythms, potentially making it a healthier option at a population level than either permanent DST, or the current system of DST time changes.60 Some sleep scientists have argued in favour of permanent standard time on these grounds.61

The drawback of permanent standard time is that it sacrifices the benefits of DST in summer altogether. Earlier summer sunsets reduce leisure time and increase the risk of evening commutes even as mornings become brighter and safer as a result. Nevertheless, the wider potential health benefits of permanent standard time make it a policy option worthy of deeper investigation and consideration.

It’s time that Congress did something about time

To avoid negatively impacting the majority of the US population while maximising flexible and healthy living conditions, Congress should:

1. Reject the Sunshine Protection Act

The benefits of the Sunshine Protection Act do not outweigh its drawbacks. While longer evenings year-round are desirable, the Act in effect only extends the existing DST regime by a further four months into winter, when evenings would still remain comparatively short, and darker mornings would have significantly more impact. On the basis of the overwhelming proportion of the population that would face sunrises after 8am in winter (and a significant proportion after 8.30am), the likely public health impacts of such a measure on the population, and the likelihood of a decline in public support in line with that experienced in the 1970s, the Sunshine Protection Act and measures to legislate permanent DST should not proceed.

2. Promote the adoption of flexible work schedules

The uptake of flexible working arrangements in urban workplaces are likely to make the benefits of DST increasingly irrelevant. While DST was once a blunt but effective means of providing urban workers with extra daylight hours, many of these workers are increasingly able to make such arrangements themselves if they wish. Flexible working arrangements now cover as many as 58 per cent of Americans, limiting the uniform impact of DST on the working population.62

In 1919, Senator Charles Townsend foreshadowed such a solution when advocating for the repeal of DST in 1919, arguing that DST “was largely an academic question which could readily be adjusted by the business interests of the country without any law on the subject.”63 In the same debate, Senator John Sharp Williams argued that “if a factory man and his labor agree to begin work an hour earlier or to quit an hour earlier, they can do so without calling upon the Government of the United States to pass a law to change God’s time, which is 12 o’clock when the sun is just above meridian.”64

“If a factory man and his labor agree to begin work an hour earlier or to quit an hour earlier, they can do so without calling upon the Government of the United States to pass a law to change God’s time.” — Senator John Sharp Williams, 1919

The United States would benefit from promoting policies that encourage flexible work schedules, which particularly benefit the urban workers that benefit from the current DST system, without sacrificing the flexibility, economic benefits and leisure options afforded to urban workers by having the potential for brighter evenings.

3. Consider amending the Uniform Time Act to abolish DST

The current system of DST achieves a balance between long evenings and dark mornings by excluding the winter months when late sunrises are undesirable. If deemed suitable and sustainable, it may be that the present DST regime can continue indefinitely. Indeed, the lack of urgency, political consensus and understanding around the issue makes the continuation of the status quo the most likely option.

However, as shown by public opinion polling, biannual confusion around the time change and intractable policy debates around DST, the present system is unpopular and there is an appetite for change.65 An extension of DST to encompass winter months solely to eliminate the inconvenience of regular time changes is likely to result in negative outcomes for limited benefit. To satisfy the public appetite for change and simplify commercial and logistical challenges, there may be cause to abolish DST altogether in favour of permanent standard time combined with greater flexibility options among the urban working population of the United States. This would permit individual Americans to tailor their own routines in line with their preferences without requiring time changes or forcing uniform adoption of a civil time heavily misaligned with solar time.

The current DST system in the United States is an increasingly anachronistic solution to a problem that can be better solved with flexibility and labour reform rather than arbitrary changes of measurement standards.


The current DST system in the United States is an increasingly anachronistic solution to a problem that can be better solved with flexibility and labour reform rather than arbitrary changes of measurement standards. Implementing permanent, year-round DST would eliminate logistically undesirable biannual time changes, but result in untenably late winter sunrises that would likely undermine the purpose of a permanent time change in the long term. A move to permanent standard time would eliminate time changes and their impact on the population and, if combined with greater workplace flexibility for urban workers, many of the benefits of the present DST system could be maintained. While seemingly trivial, any changes to DST warrant close study by Congress to avoid unintended, and far-reaching, consequences that repeat the mistakes of the past.