Daylight Saving Time (DST)

May 29, 2018 – September 30, 2020 R45208

Daylight Saving Time (DST)
Updated September 30, 2020
Congressional Research Service
https://crsreports.congress.gov
R45208

Daylight Saving Time (DST)

Summary
Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in most
parts of the United States are set one hour ahead of standard time. DST begins on the second
Sunday in March and ends on the first Sunday in November. The beginning and ending dates are
set in statute. Congressional interest in the potential benefits and costs of DST has resulted in
changes to DST observance since it was first adopted in the United States in 1918.
The United States established standard time zones and DST through the Calder Act, also known
as the Standard Time Act of 1918. The issue of consistency in time observance was further
clarified by the Uniform Time Act of 1966. These laws as amended allow a state to exempt
itself—or parts of the state that lie within a different time zone—from DST observance. These
laws as amended also authorize the Department of Transportation (DOT) to regulate standard
time zone boundaries and DST. The time period for DST was changed most recently in the
Energy Policy Act of 2005 (EPACT 2005; P.L. 109-58).
Congress has required several agencies to study the effects of changes in DST observance. In
1974, DOT reported that the potential benefits to energy conservation, traffic safety, and
reductions in violent crime were minimal. In 2008, the Department of Energy assessed the effects
to national energy consumption of extending DST as changed in EPACT 2005 and found a
reduction in total primary energy consumption of 0.02%. Other studies have examined potential
health effects associated with the spring and fall transition to DST and found a cumulative effect
of sleep loss and increased risk for incidence of acute myocardial infarction (heart attacks) in
specific subgroups.
Only Congress can change the length of the DST observance period; however, since 2015, at least
45 states have proposed legislation to change their observance of DST. These efforts include
proposals to exempt a state from DST observance, which is allowable under existing law, and
proposals that would effectively establish permanent DST, which would require Congress to
amend the Uniform Time Act of 1966. Most of the proposals have not passed. Eleven states have
enacted permanent DST legislation: Delaware, Florida, Idaho, Louisiana, Maine, Oregon, South
Carolina, Utah, Tennessee, Washington, and Wyoming. In addition, Arkansas and Georgia have
adopted resolutions in support of permanent DST.
Congress may consider whether to make additional changes to DST observance or standard time.
Several bills have been introduced in the 116th Congress that would make changes to standard
time to effectively implement year-round DST. On March 12, 2018, the House Committee on
Energy and Commerce sent a letter to DOT requesting updated information related to DST and
standard time. On June 20, 2018, DOT informed the committee that it had initiated a literature
review of the issue and would share the results with the committee, but as of September 2020
these results have not been submitted.

Congressional Research Service

Daylight Saving Time (DST)

Introduction
Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in most
parts of the United States are set one hour ahead of standard time. The beginning and ending
dates and times—the second Sunday in March at two o’clock ante meridian (2 a.m.) and the first
Sunday in November at 2 a.m.—are set in statute.1 Congressional interest in the potential benefits
and costs of DST has resulted in changes to DST observance since it was first adopted in the
United States.
Congress may consider whether to make additional changes to DST observance or standard time.
Congress may also consider whether additional examination of potential benefits and costs of
DST observance would be informative. This report presents a selected history of DST in the
United States and includes a summary of potential effects, selected state actions related to DST or
standard time, and federal legislation that has been introduced related to DST in the 115th and
116th Congresses.
The Development of Standard Time and Daylight
Saving Time
The development of railroads led to the creation of a standard time in the United States. To reduce
the confusion resulting from locally established “sun times” at railroad terminals, U.S. and
Canadian railroads adopted four standard time zones in 1883.2 The four established time zones
were the Eastern, Central, Mountain, and Pacific. Adoption of time zones at the local level was
influenced by the time zones adopted by the railroads.
The Calder Act or the Standard Time Act of 1918
In 1918, Congress passed an act to provide standard time for the United States (also known as the
Calder Act and the Standard Time Act of 1918).3 The act established five standard time zones; the
fifth time zone was established to include Alaska. It authorized the Interstate Commerce
Commission (ICC) to fix the time zone boundaries within the United States and to change them
as necessary. The act also set a summer DST to begin on the last Sunday of March and conclude
on the last Sunday in October. The adoption of DST in the United States was preceded by
adoption of DST in Europe during World War I.4 After World War I, Congress abolished summer
DST at the federal level, although it remained a local option with some states continuing to
observe it.

1 See 15 U.S.C. §260a. Effectively, this means that in the United States, each time zone switches to and from Daylight
Saving Time (DST) at a different time. This is in contrast to the European Union, where all time zones change at the
same moment.
2 “Sun times” refer to the apparent solar times established at locations based upon the apparent motion of the sun (i.e.,
noon would be the time of day when it appears that the sun has reached its highest point in the sky). Department of
Transportation (DOT), Uniform Time, February 13, 2015, https://www.transportation.gov/regulations/time-act.
3 An Act to save daylight and to provide standard time for the United States, March 19, 1918, ch. 24, 40 Stat. 450 (15
U.S.C. §§261 et seq.).
4 In an effort to conserve fuel, Germany began observing DST in 1916, and as the war progressed, the rest of Europe
adopted DST as well.
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The Uniform Time Act of 1966
In 1961, the Interstate Commerce Commission (ICC) recommended that Congress reexamine “the
entire field of standard time.”5 According to the ICC, “the growing inconvenience, confusion, and
sometimes danger, resulting from this time situation would seem too great a price to pay merely
to preserve the right of local option in matters of standard time.”6 The reexamination resulted in
the Uniform Time Act of 1966 (P.L. 89-387).7 The act mandated standard time within the
established time zones and specified the observance period for DST: clocks would be advanced
one hour beginning at 2:00 a.m. on the last Sunday in April and turned back one hour at 2:00 a.m.
on the last Sunday in October. States were allowed to exempt themselves from DST as long as the
entire state did so. If a state chose to observe DST, the time changes were required to begin and
end on the established dates. The ICC was authorized with implementing the act until the
authorities were transferred to the Department of Transportation (DOT), which occurred in
October 1966 through the Department of Transportation Act (P.L. 89-670).8
In 1972, the Uniform Time Act was amended (P.L. 92-267) to also allow states that were split
between time zones9 to exempt from DST that part of the state lying within a different time zone.
The following states and territories do not observe DST: American Samoa, most of Arizona,
Guam, Hawaii, the Northern Mariana Islands, Puerto Rico, and the Virgin Islands.10
Other Changes to Standard Time and DST
Temporary Year-Round DST
Year-round DST has been implemented twice on a temporary basis in the United States. In 1942,
Congress enacted a law to institute year-round DST, which became known as “War Time.”11 The
law advanced the standard time for each time zone by one hour to be in effect until six months
after the war ended or earlier if Congress required in a subsequent concurrent resolution. After the

5 Interstate Commerce Commission (ICC), 75th Annual Report of the Interstate Commerce Commission: Fiscal Year
Ended June 30, 1961, H. Doc. 262, Washington, DC, 1961, p. 148; ICC, Interstate Commerce Commission Activities:
Supplement to the 75th Annual Report, H.Doc. 369, Washington, DC, 1962, p. 229.
6 ICC, 75th Annual Report of the Interstate Commerce Commission: Fiscal Year Ended June 30, 1961, H.Doc. 262,
Washington, DC, 1961, p. 146.
7 Uniform Time Act of 1966 as amended, 15 U.S.C. §§260-267.
8 DOT regulates standard time zone boundaries and DST per 49 C.F.R. §71.
9 Fourteen states are divided between two time zones, ranging from those states almost evenly divided between two
zones (Kentucky, South Dakota, Tennessee) to those with only a small area of the state in a second time zone (Kansas,
Nevada, Oregon, Texas). The 14 states are: Florida, Indiana, Kentucky, Michigan, and Tennessee split between the
Eastern and Central time zones; Kansas, Nebraska, North Dakota, South Dakota, and Texas split between the Central
and Mountain time zones; Idaho, Nevada, and Oregon split between Mountain and Pacific time zones; and Alaska split
between Alaskan and Hawaii-Aleutian time zones.
10 Department of Transportation, Daylight Saving Time, March 10, 2014, https://www.transportation.gov/regulations/
daylight-saving-time. According to Haw. Rev. Stat. Ann. §1-31, Hawaii exempted itself in 1967. According to Ariz.
Rev. Stat. §1-242, Arizona exempted itself in 1968.
11 According to the ICC, “War Time” was a strategy “to assist in dissipating evening peakloads, which were threatening
to exceed the capacity of our limited power facilities available for nondefense purposes, and which were even greater in
winter than in summer months.” ICC, Interstate Commerce Commission Activities: Supplement to the 75th Annual
Report, H.Doc. 369, Washington, DC, 1962, p. 225. January 20, 1942, entitled “An Act to promote the national
security and defense by establishing daylight saving time.”
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conclusion of World War II, Congress terminated DST, and War Time concluded on the last
Sunday in September 1945.12 During the 1973 oil embargo by the Organization of Arab
Petroleum Exporting Countries (OAPEC), Congress enacted the Emergency Daylight Saving
Time Energy Conservation Act of 1973 (P.L. 93-182), which established a trial period of year-
round DST, from January 6, 1974, to April 27, 1975.13 An interim report by DOT recommended
amending the trial period to include four months of standard time, and Congress amended the act
in October 1974 by P.L. 93-434, which required a return to standard time for the period beginning
October 27, 1974, and ending February 23, 1975, when DST resumed.14 When the trial period
ended in 1975, the country returned to observing summer DST (with the aforementioned
exceptions).
Adjustments to the Length of DST Observance
Congress has made additional changes to the Uniform Time Act. In 1986, Congress enacted P.L.
99-359, which changed the beginning of DST from the last Sunday in April to the first Sunday in
April. In 2005, Congress enacted the Energy Policy Act of 2005 (P.L. 109-58). Section 110 of this
act amended the Uniform Time Act, by further changing DST to begin the second Sunday in
March and end the first Sunday in November (it had previously ended the last Sunday in
October); this DST period remains in effect today. The act required the Secretary of the
Department of Energy (DOE) to report to Congress on the impact of extended DST on energy
consumption in the United States (see section on “Energy Savings”).15
Other Changes
Other legislative changes addressed time zones. P.L. 106-564 amended the Calder Act to increase
from eight to nine the number of standard time zones in the territory of the United States, creating
Chamorro standard time, which includes Guam and the Commonwealth of the Northern Mariana
Islands.16 It also amended the Uniform Time Act of 1966 to include Guam and the Northern
Mariana Islands in the definition of “State.”17 In 2007, the 110th Congress enacted the America
COMPETES Act (P.L. 110-69). Section 3013 of this act made changes to the Uniform Time Act
regarding Standard Time in the United States, including a change to Idaho’s time zone.18

12 56 Stat. 9, An Act to provide for termination of daylight saving time, P.L. 79-403, 79th Congress, 2nd Session.
13 The act also required DOT to examine the effects of the act including safety of children traveling to and from school
and school hours. The study is discussed in “Potential Effects of DST” of this report. See DOT, The Year-Round
Daylight Saving Time Study: A Report to Congress from the Secretary of Transportation, (Interim Report),
Washington, DC, June 1974; DOT, The Daylight Saving Time Study: A Report to Congress from the Secretary of
Transportation (Final Report), Washington, DC, September 1975.
14 DOT, The Daylight Saving Time Study: A Report to Congress from the Secretary of Transportation (Final Report),
Washington, DC, September 1975, p. 20.
15 U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Impact of Extended
Daylight Saving Time on National Energy Consumption, October 2008, at http://www1.eere.energy.gov/ba/pba/pdfs/
epact_sec_110_edst_report_to_congress_2008.pdf.
16 According to 49 C.F.R. §71.1(c), “The time zones established by the Standard Time Zone Act, as amended by the
Uniform Time Act of 1966, are Atlantic, eastern, central, mountain, Pacific, Alaska, Hawaii-Aleutian, Samoa, and
Chamorro.”
17 By including Guam and the Northern Mariana Islands in the definition of “State,” these territories may exempt
themselves from DST as provided in the Uniform Time Act of 1966.
18 The Congressional Research Service (CRS) identified no DST-related legislation or legislation to amend the Uniform
Time Act after enactment of P.L. 110-69 until the 115th Congress. CRS searched the Congress.gov database to identify
DST-related legislation using a combination of keywords or phrases and proximity locators. Keywords and phrases
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Potential Effects of DST
Support and opposition to changes in DST observance often focus on its potential effects. Those
in favor of extending DST observance reportedly argue that the extended daylight in the evening
promotes economic activity, including tourism.19 Those against extending DST observance
reportedly argue that losing an hour of daylight in the morning could negatively affect golf course
operations, ski resorts, and schoolchildren’s morning commutes.20 A number of studies have been
conducted on DST’s effects on safety, energy savings, and health. A selection of these—including
studies mandated by Congress—is discussed in this section. This is not a comprehensive review
of the literature.
Congress has required several agencies to evaluate the effects of DST. DOT provided an interim
evaluation and final report on the operation and effects of DST in 1974 and 1975.21 The interim
report’s findings were inconclusive, stating that the observed effects were “so small that they
could not in general be reliably separated from effects of other changes occurring at the time.”22
The report concluded that, “there is no unambiguous direct evidence that [the measurable effects
of year-round daylight saving time] were either beneficial or harmful.”23 DOT reported that
“modest overall benefits might be realized by a shift from the historic six-month DST (May
through October) [to year-round DST] in areas of energy conservation, overall traffic safety, and
reduced violent crime.” DOT also reported that these potential benefits would be minimal and
difficult to distinguish from seasonal variations and fluctuations in energy prices.
Safety
After DOT submitted the report to Congress in 1975, Congress directed the National Bureau of
Standards (NBS)24 to conduct a technical evaluation of the DOT study and to deliver a report to
Congress. In its report, NBS found no significant energy savings or differences in traffic
fatalities.25 Although statistically significant evidence was found of increased fatalities among
school-age children in the mornings during the four-month period January-April 1974 as
compared with the same period (non-DST) of 1973, NBS stated that

included the following: daylight saving time; D.S.T.; permanent; Uniform Time Act of 1966; standard time; saving
sunshine; and time zone(s).
19 See, for example, Orrin Hatch, “Daylight Saving Time Should Be Permanent. The Pandemic Shows Us Why,” Time,
September 14, 2020, https://time.com/5888112/daylight-savings-time-permanent/; Lance Shearer, “No ‘Fall Back’
Position? Florida Legislature Passes Full-Time Daylight Saving Time,” Marco Eagle, March 9, 2018,
https://www.marconews.com/story/news/2018/03/09/no-fall-back-position-florida-legislature-passes-full-time-
daylight-saving-time/406906002/.
20 See for example, ibid; Zach Thaxton, “Bill Proposing Permanent Daylight Saving Time in Colorado Dies,” KOAA
News 5, March 13, 2017.
21 DOT, The Year-Round Daylight Saving Time Study: A Report to Congress from the Secretary of Transportation,
(Interim Report), Washington, DC, June 1974; DOT, The Daylight Saving Time Study: A Report to Congress from the
Secretary of Transportation (Final Report), Washington, DC, September 1975.
22 Ibid., p. ES-1.
23 Ibid., p. ES-2.
24 The National Bureau of Standards was renamed the National Institute of Standards and Technology (NIST) in 1988.
25 National Bureau of Standards, Report to Congress: Review and Technical Evaluation of the DOT Daylight Saving
Time Study, April 1976 (Corrected June 1976), p. E-3 (hereinafter, NIST, Report to Congress: Review and Technical
Evaluation of the DOT Daylight Saving Time Study).
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This increase cannot be simply interpreted as ‘DST effect,’ in view of the many other
factors that influence traffic fatalities. When the months of January through April are
considered individually, there is no statistically significant difference between 1973 and
1974 with respect to school-age children fatal accidents in the morning for the months of
March and April.26
Other studies have found that the short-term effect of DST on crashes is not statistically
significant.27 One review of the scientific literature found that while findings on the short-term
effects of DST were inconsistent, the long-term effects of DST suggest a positive effect (i.e., DST
is associated with a reduction in collisions, injuries, and fatalities).28 However, the long-term
results “may be attributable to factors other than light.”29
Energy Savings
As part of the Energy Policy Act of 2005 (P.L. 109-58), Congress directed DOE to evaluate
energy savings resulting from extending DST. In 2008, DOE submitted a report to Congress on
the effects of the extended DST on U.S. energy consumption.30 DOE found that the total
electricity savings associated with the extended DST corresponded to 0.03% decrease in
electricity consumption in 2007. In terms of primary energy consumption, this represents
approximately 0.02% of total U.S. energy consumption in 2007.31 Regionally, areas in the
northern United States exhibited larger electricity savings than areas in the southern United
States. DOE reported that there was insufficient statistical evidence to indicate whether extended
DST “had any measurable impact on motor gasoline consumption for passenger vehicles or traffic
volume in 2007.”32
Literature reviews have reported similar savings as reported by DOE.33 At least one empirical
study based in Indiana found that DST increases electricity demand.34 Aries and Newsham (2008)
concluded that “existing knowledge about how DST affects electricity use is limited, incomplete,
or contradictory.”35 Havranek et al. (2018) conducted a literature review and found that

26 NIST, Report to Congress: Review and Technical Evaluation of the DOT Daylight Saving Time Study, p. E-3.
27 A. Huang and D. Levinson, “The Effects of Daylight Saving Time on Vehicle Crashes in Minnesota,” Journal of
Safety Research, vol. 41 issue 6 (December 2010), pp. 513-520. T. Lahti et al., “Daylight Saving Time Transitions and
Road Traffic Accidents,” Journal of Environmental and Public Health, vol. 2010, Article ID 657167,
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2905900/.
28 Rachel N. Carey and Kiran M. Sarma, “Impact of Daylight Saving Time on Road Traffic Collision Risk: A
Systematic Review,” BMJ Open, vol. 7, issue 6 (July 2017), p. e014319 (hereinafter, Carey, “Impact of Daylight
Saving Time on Road Traffic Collision Risk”).
29 Carey, “Impact of Daylight Saving Time on Road Traffic Collision Risk.” Other risk factors that can affect road
traffic collisions in the long-term include traffic flow and weather conditions.
30 Extended DST refers to changing the start date from the first Sunday in April to the second Sunday in March and the
end date from the last Sunday in October to the first Sunday in November. U.S. Department of Energy (DOE), Impact
of Extended Daylight Saving Time on National Energy Consumption: Report to Congress, October 2008 (hereinafter,
DOE, Impact of Extended Daylight Saving Time on National Energy Consumption, 2008).
31 DOE, Impact of Extended Daylight Saving Time on National Energy Consumption, 2008, p. i.
32 DOE, Impact of Extended Daylight Saving Time on National Energy Consumption, 2008., p. 2.
33 M.B. Aries and G.R. Newsham, “Effect of Daylight Saving Time on Lighting Energy Use: A Literature Review,”
Energy Policy, vol. 36 issue 6 (June 2008), pp. 1858-1866.
34 M.J. Kotchten, “Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana,” The
Review of Economics and Statistics, vol. 93, issue 4 (November 2011), pp. 1172–1185.
35 M.B. Aries and G.R. Newsham, “Effect of Daylight Saving Time on Lighting Energy Use: A Literature Review,”
Energy Policy, vol. 36, issue 6 (June 2008), pp. 1858-1866.
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“electricity savings are larger for countries [or areas] farther away from the equator, while
subtropical regions consume more electricity because of DST.”36
Health
Several studies have examined potential health effects related to the semiannual changing of the
clock per DST. Harrison (2013) reviewed the effect of DST on sleep, and found that data from the
spring and fall transition periods suggest a cumulative effect of sleep loss.37 Jiddou et al. (2013)
evaluated the incidence of acute myocardial infarction (AMI, or heart attack) with transitions to
and from DST, and they found evidence consistent with previously reported trends that “shifts to
and from DST might be associated with transient increases and decreases in the incidence of
AMI, respectively.”38 A study from 2015 concluded that “specific subgroups such as men and
persons with a history of AMI or prior treatment with angiotensin-converting-enzyme (ACE)
inhibitors may have a higher risk for AMI during DST.”39 In 2020, the American Academy of
Sleep Medicine recommended ceasing the seasonal changing of clocks in favor of a year-round
fixed time, without stating a preference for year-round DST or year-round standard time.40
Although potential chronic effects of DST are less studied, according to the authors, “the acute
transition from standard time to daylight saving time incurs significant public health and safety
risks, including increased risk of adverse cardiovascular events, mood disorders, and motor
vehicle crashes.”41
Department of Transportation’s Regulation of Time
Zones
Although states may exempt themselves, in whole or in part, from DST, they cannot
independently change time zones or alter the length of DST (i.e., DST begins and ends on
statutorily mandated dates). There are two ways in which an area can be moved from one time
zone to another: by regulation or by statute.
Under the Standard Time Act of 1918, as amended by the Uniform Time Act of 1966, moving a
state or an area within a state from one time zone to another requires DOT regulation. Such a
request can be made only by certain political authorities in an area.42 For example, if the request

36 Tomas Havranek, Dominik Herman, and Zuzana Irsova, “Does Daylight Saving Save Electricity? A Meta-Analysis,”
The Energy Journal, vol. 39, no. 2 (2018), pp. 35-61.
37 Y. Harrison, “The Impact of Daylight Saving Time on Sleep and Related Behaviours,” Sleep Medicine Reviews, vol.
17, issue 4 (August 2013), pp. 285-292.
38 Acute myocardial infarction (AMI) is the medical name for a heart attack, which refers to a blockage of blood flow
to the heart muscle. M.R. Jiddou et al., “Incidence of Myocardial Infarction with Shifts to and from Daylight Savings
Time,” The American Journal of Cardiology, vol.111, issue 5 (March 1, 2013), pp. 631-635.
39 ACE inhibitors refer to angiotensin converting enzyme inhibitors, which are medications that enlarge or dilate blood
vessels, lowering blood pressure. I. Kirchberger, K. Wolf, and M. Heier, et al., “Are Daylight Saving Time Transitions
Associated with Changes in Myocardial Infarction Incidence? Results from the German MONICA/KORA Myocardial
Infarction Registry,” BMC Public Health, vol. 15 (August 14, 2015), p. 778. https://doi.org/10.1186/s12889-015-2124-
4.
40 M.A. Rishi et al. “Daylight Saving Time: an American Academy of Sleep Medicine Position Statement,” Journal of
Clinical Sleep Medicine, August 26, 2020, https://doi.org/10.5664/jcsm.8780 (hereinafter, Rishi et al., “Daylight
Saving Time: an American Academy of Sleep Medicine Position Statement”).
41 Rishi et al., “Daylight Saving Time: an American Academy of Sleep Medicine Position Statement.”
42 According to DOT, “DOT will generally begin a rulemaking proceeding to change a time zone boundary if the
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for change is for one or more counties, the board (or boards) of county commissioners would
make the request. If the request is for a state, the governor or the legislature would make the
request.
The principles for deciding whether to change the time zone for an area are the “convenience of
commerce and the existing junction points and division points of common carriers engaged in
interstate or foreign commerce.”43 The standard for deciding whether to change a time zone
includes consideration of all the impacts upon a community that is requesting a change in its
standard of time. The “convenience of commerce” is defined broadly to consider such
circumstances as the shipment of goods within the community; the origin of television and radio
broadcasts; the areas where most residents work, attend school, worship, or receive health care;
the location of airports, railways, and bus stations; and the major elements of the community’s
economy.44 DOT considers this information in making its decision on time zone change
proposals.45
After receiving a request, DOT determines whether it meets the minimum statutory criteria before
issuing a notice of proposed rulemaking, under which it would solicit public comment and
schedule a public hearing. Usually the hearing is held in the area requesting the change so that
affected parties can be represented. After the comment period closes, comments are reviewed and
final action is taken. If the Secretary of Transportation agrees that the statutory requirement has
been met, the change would be instituted, usually at the next changeover to or from DST.46
Selected State Actions to Change DST Observance
Even though a state cannot unilaterally go on year-round DST, a majority of states have initiated
efforts to change the summer observance of DST. Many state legislative actions have occurred
since 2015.47 CRS identified 45 states that have introduced legislation that would support changes
to the summer observance of DST as of August 2020.48 At least 40 states have introduced
legislation proposing some variation of permanent DST.49 Similarly, at least 30 states have

highest elected officials in the area submit a petition requesting a time zone change and provide adequate data
supporting the proposed change.” See DOT, “Standard Time Zone Boundary in Southwest Indiana,” 72 Federal
Register 54367, September 25, 2007.
43 15 U.S.C. §261.
44 DOT, “Procedure for Moving an Area from One Time Zone to Another,” April 30, 2013,
https://www.transportation.gov/regulations/procedure-moving-area-one-time-zone-another.
45 For an example of the procedure that resulted in a decision by DOT that the requested proposed change suited “the
convenience of commerce,” see DOT, “Relocation of Standard Time Zone Boundary in the State of North Dakota:
Mercer County,” 75 Federal Register 60004-60008, September 29, 2010.
46 For example, the change in the standard time zone boundary for Mercer County, ND, took effect at the conclusion of
DST observance on Sunday, November 7, 2010; see, DOT, “Relocation of Standard Time Zone Boundary in the State
of North Dakota: Mercer County,” 75 Federal Register 60004, September 29, 2010.
47 Prior to 2015, legislation was introduced in the Louisiana legislature in 2003, 2006, and 2010 that sought to make
DST permanent standard time.
48 CRS identified state actions through searches (conducted on May 22, 2018, May 17, 2019, and July 15, 2020) that
included news articles, the National Council of State Legislatures website, Lexis Advance database, and state
legislature websites.
49 States have taken different legislative approaches. Some would seek to implement year-round DST to advance time
by one hour compared to the previous time. Others would request DOT to change a state’s time zone to one that is one
hour ahead and then exempting the state from DST observance, which would achieve the same effect—advance time
by one hour compared with the previous time.
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introduced legislation to establish permanent standard time, and 5 states have introduced
legislation to study the effects of DST or the effects of changing the observance of DST.
Some of the legislative proposals, if enacted, would be contingent upon the actions of
neighboring states. For example, Oregon’s S.B. 1267 (2020) would require the entire state to
observe permanent DST “at such time as the state of Washington makes daylight saving time the
permanent time of the state and all of its political subdivisions”50 and Delaware’s S.B. 73 (2019)
would place the state in the Atlantic Standard Time zone if Pennsylvania, New Jersey and
Maryland enact similar legislation. Both bills have been enacted and signed into law.
In addition, four states in New England—Maine, Massachusetts, New Hampshire, and Rhode
Island—have reportedly created commissions or introduced proposals to move to year-round
DST.51 These proposals would change the standard time zone from Eastern Standard Time to
Atlantic Standard Time (i.e., one hour ahead), which would effectively adopt DST all year
round.52 In November 2017, the Massachusetts Special Commission on the Commonwealth’s
Time Zone submitted its recommendation “that under certain circumstances the Commonwealth
could make a data-driven case for moving to the Atlantic Time Zone year-round (effectively
observing year-round DST).”53
Table 1 lists the states that have introduced legislation proposing changes to the summer
observance of DST or have proposed to study the effects of DST.
Table 1. States Introducing Daylight Saving Time Observance Legislation, by Type:
January 2015-September 2020
State
Permanent DST
Permanent Standard Time
Study the Effects of DST
Alabama
x
x

Alaska
x
x

Arkansas
xa
x

California
x
x

Colorado
x
x

Connecticut
x
x

Delaware
xb

Florida
xc
x

Georgia
xd
x

Idaho
xe
x

Il inois
x
x

Iowa
x
x

Kansas

x

Kentucky
x

Louisiana
xf

x

50 Oregon is located within both the Pacific Time zone and the Mountain Time zone.
51 Maggie Astor, “Year-Round Daylight Saving Time? Florida Says Yes, but It’s Not So Simple,” The New York Times,
March 8, 2018, https://www.nytimes.com/2018/03/08/us/daylight-saving-time-florida.html.
52 Nik DeCosta-Klipa, “Could New England Actually Change Time Zones—And What Happens If It Does?,”
Boston.com, November 5, 2017, https://www.boston.com/news/local-news/2017/11/05/new-england-atlantic-time-
zone.
53 Commonwealth of Massachusetts Special Commission, Report of the Special Commission on the Commonwealth’s
Time Zone, November 1, 2017, p. 25.
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State
Permanent DST
Permanent Standard Time
Study the Effects of DST
Maine
xg

Maryland
x

Massachusetts
x

x
Michigan
x
x

Minnesota
x
x

Mississippi
x
x

Missouri
x
x

Montana

x

Nebraska
x
x

Nevada
x

New Hampshire
x

New Jersey
x

New Mexico
x
x

New York
x
x
x
North Carolina
x

North Dakota

x

Ohio
x

Oklahoma
x
x

Oregon
xh
x

Pennsylvania
x
x
x
Rhode Island
x

South Carolina
xi

x
South Dakota
x
x

Tennessee
xj

Texas

x

Utah
xk
x

Vermont
x
x

Washington
xl
x

West Virginia
x

Wyoming
xm
x

Sources: Congressional Research Service (CRS) based on Lexis Advance database (“Statutes and Legislation”
database); state legislature websites/databases; National Council of State Legislature (NACL) website; CQ.com’s
StateTrack database.
Notes: The table reflects those legislative efforts by states that were identified in the searches conducted on
May 22, 2018, May 17, 2019, and July 15, 2020.
a. Arkansas adopted H.R. 1034, a non-binding resolution to establish permanent DST, on March 12, 2019.
b. Delaware’s House and Senate passed S.B. 73 (“An Act to Adopt Eastern Daylight Time Year-round”) and
the bil was signed into law by Governor John Carney on August 12. 2019. The bil requires the governor to
request that the U.S. Secretary of Transportation place Delaware in the Atlantic Standard Time zone if
Pennsylvania, New Jersey and Maryland each do the same.
c. Florida’s House and Senate passed H.B. 1013 (“Sunshine Protection Act”) and the bil was approved by
Governor Scott on March 23, 2018. The bil would institute year-round DST in Florida “if the United States
Congress amends 15 U.S.C. §260a to authorize states to observe daylight saving time year-round.”
d. Georgia’s House of Representative adopted non-binding resolution H.R. 1240, to urge the federal
government to allow states to switch to permanent DST, on March 9, 2020.
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e. Idaho’s House and Senate passed S.B. 1267 and Governor Brad Little signed the bil into law on March 16,
2020. The bil would make DST the permanent time for all political subdivisions of Idaho “at such time as
the state of Washington makes daylight saving time the permanent time of the state and all of its political
subdivisions.”
f.
Louisiana’s House and Senate passed H.B. 132, which establishes DST as the official time year-round, subject
to an authorizing federal law. Governor John Bel Edwards signed the bil into law on June 9, 2020.
g. Maine’s House and Senate passed H.P. 659 (L.D. 885), an act “To Adopt Eastern Daylight Time Year-
round.” Governor Janet Mil s received the passed legislation on June 11, 2019, which became law without
the Governor’s signature.
h. Oregon’s House and Senate passed S.B. 320, which abolishes the annual change in time from standard time
to DST and maintains Oregon on DST. The bil refers the act to the people of Oregon for their approval or
rejection at the next regular general election. Governor Kate Brown signed the bil into law on June 17,
2019.
i.
South Carolina’s House and Senate passed S.11 and Governor Henry McMaster signed the bil into law on
February 7, 2020. The bil would make DST the year-round standard time for the entire state if the U.S.
Congress amends related federal law to allow states to observe DST year-round.
j.
Tennessee’s House and Senate passed H.B. 247 and Governor Bil Lee signed the bil on May 8, 2019. H.B.
247 would establish “daylight saving time as the standard time in Tennessee,” subject to authorization to do
so from the U.S. Congress.
k. Utah’s Senate and House passed S.B. 59 and Governor Gary Herbert signed the bil into law on March 28,
2020. The bil , subject to congressional authorization, would “place Utah and all political subdivisions in
Utah on year-round mountain daylight time.”
l.
Washington’s House and Senate passed H.B. 1196 (“Allowing for the year round observation of daylight
saving time”) and the bil was signed into law by Governor Jay Inslee on May 8, 2019. The bil is subject to
the U.S. Congress amending federal law and authorizing states to observe DST year round.
m. Wyoming’s House and Senate passed H.B. 44 and Governor Mark Gordon signed the bil into law on March
24, 2020. The bil , subject to congressional authorization, would authorize the entire state of Wyoming to
observe mountain daylight time.
Since 2018, 11 states have enacted permanent DST legislation: Florida in 2018; Delaware, Maine,
Oregon, Tennessee, and Washington State in 2019; and Idaho, Louisiana, South Carolina, Utah,
and Wyoming in 2020. In addition, Arkansas adopted a nonbinding resolution to establish
permanent DST, on March 12, 2019, and Georgia similarly adopted a nonbinding resolution on
March 9, 2020, to urge the federal government to allow states to switch to permanent DST.
Another recent course of action to establish permanent DST or permanent standard time is by
state-wide ballot measures. Several states have either voted on a ballot measure (California) or
have ballot initiatives, some of which could appear in the November 2020 general election
(Colorado, Missouri, and Texas).
Californians voted on Proposition (Prop) 7 in the November 6, 2018, general election and the
measure passed, receiving nearly 60% of the votes.54 Prop 7 allows the California State
Legislature to vote on establishing permanent DST in the state. The measure requires both
chambers in the legislature to pass a bill by a two-thirds majority vote and the change to be
“consistent with federal law.”55 In response to the passage of Prop 7, the California State
Assembly introduced AB-7 in December 2018 and passed the bill (72-8) on May 9, 2019. AB-7
currently remains with the State Senate, which cancelled a scheduled June 2019 hearing on the

54 California Secretary of State, California Statement of Vote—November 6, 2018, p.16.
55 California Secretary of State, California General Election, November 6, 2018; “Proposition 7 Summary.”
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bill and has taken no further legislative action. 56 In March 2020, A.J.R. 33 was introduced, which
would urge the federal government to allow a state to adopt DST year-round.57
In March 2019, the Texas State House of Representatives introduced both a joint resolution
(H.J.R. 117) and a bill (H.B. 3784) to amend the state constitution and authorize “a statewide
referendum allowing voters to indicate a preference for observing standard time year-round or
observing daylight saving time year-round.”58 The State House passed both the resolution—with
a required two-thirds majority (133-9)—and the bill on April 24 and April 25, 2019,
respectively.59 The State Senate took no further legislative action on H.J.R. 117 or H.B. 3784 and
the 86th legislative session (2019) ended on May 27, 2019. The referendum will not appear on the
state-wide November 2020 ballot as the 87th legislative session does not convene until January
12, 2021.60
Colorado and Missouri both approved DST initiatives that could have appeared on their
respective state-wide ballots for the November 2020 general election. Colorado’s Initiative 54
(“Daylight Saving Time”) would have made “the year-round standard time in Colorado daylight
saving time that is one hour later than United States Mountain Standard time.”61 Missouri’s
Initiative Petition 55 would have amended the state constitution “to eliminate daylight saving
time in Missouri.”62 Both initiatives required, but failed to gather, the specified number of valid
signatures from registered voters by a set deadline date to qualify for the November 2020 ballot.63
In Colorado, the petition for Initiative 54 expired on October 14, 2019.64 The petition for
Missouri’s Initiative 55 expired on May 3, 2019.65

56 For more information on AB-7, see https://leginfo.legislature.ca.gov/faces/billHistoryClient.xhtml?bill_id=
201920200AB7.
57 For more information on A.J.R. 33, see http://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=
201920200AJR33.
58 For more information on H.J.R. 117 and H.B. 3784, see https://capitol.texas.gov/BillLookup/Actions.aspx?LegSess=
86R&Bill=HJR117 and https://capitol.texas.gov/BillLookup/Actions.aspx?LegSess=86R&Bill=HB3784.
59 According to the Texas Legislative Council (TLC), “Joint resolutions proposing amendments to the Texas
Constitution require a vote of two-thirds of the total membership of each chamber for adoption. Other joint resolutions
require a simple majority vote in each chamber for adoption.” See TLC, “The Legislative Process in Texas,” November
2018, p. 7.
60 For more information on Texas state legislative sessions, see https://lrl.texas.gov/sessions/sessionYears.cfm.
61 For more information on Colorado Initiative 54, see https://www.sos.state.co.us/pubs/elections/Initiatives/titleBoard/
index.html.
62 For more information on Missouri Initiative Petition 55, see https://www.sos.mo.gov/petitions/
2020IPcirculation#2020055.
63 For number of required signatures and specified deadline dates, see https://ballotpedia.org/
Colorado_Permanent_Daylight_Saving_Time_Initiative_(2019) and https://ballotpedia.org/
Missouri_End_Daylight_Saving_Time_Initiative_(2020).
64 For more information on Colorado Initiative 54, see https://www.sos.state.co.us/pubs/elections/Initiatives/titleBoard/
index.html.
65 For more information on Missouri Initiative 55, see https://www.ballotpedia.org/
Missouri_End_Daylight_Saving_Time_Initiative_(2020); Ballotpedia’s webpage for Missouri Initiative 55; and
https://www.sos.mo.gov/petitions/2020IPcirculation#2020055.
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Ending the Changing of Clocks in the European Union
In the European Union (EU), the time period for DST (referred to as the “Summer-time period”) begins at 1 a.m.
Greenwich Mean Time (GMT) on the last Sunday in March and ends at 1 a.m. GMT on the last Sunday in October
in all member states.66 On March 26, 2019, the European Parliament voted in favor of a proposal to discontinue
the seasonal observance beginning in 2021.67 The proposal would allow EU member states to decide whether to
advance to summer time in March of 2021 and remain in summer time thereafter, or to revert to standard time
(“winter time”) in October of 2021 and remain in winter time thereafter. Member states were to notify the
European Commission (the EU’s executive body) by April 1, 2020, at the latest, as to the decision to observe
summer time or winter time.68 According to the text approved by the European Parliament, the decision should
take into account “citizens' preferences, geographical variations, regional differences, standard working
arrangements and other factors.” The proposal would allow postponement of the application of the directive to
protect the functioning of the internal market. In addition, the proposal requires an assessment of the application
and implementation of the directive to be submitted to the European Parliament and to the Council of the EU (in
which the member states are represented) by December 31, 2025. The Council would also need to approve the
proposal to end the seasonal time change for it to take effect as EU law. As of July 20, 2020, the European
Parliament has taken no further action.
Potential Issues for Congress
Congress may again consider whether to make changes to DST observance or standard time. In
the 115th Congress, four bills were introduced that would have made changes to standard time.
The four bills introduced were two sets of related House and Senate bills: the Sunshine State Act
(S. 2536 and H.R. 5278) and the Sunshine Protection Act of 2018 (S. 2537 and H.R. 5279).
In the 116th Congress, several bills have been introduced that would allow states to observe DST
year-round: a set of House and Senate companion bills, the Sunshine Protection Act of 2019 (S.
670 and H.R. 1556); three stand-alone bills, H.R. 1601 (Daylight Act), H.R. 2389, and S. 4582.
The Sunshine Protection Act of 2019 would make DST permanent for most states and areas in the
United States by advancing standard time one hour (with exemptions for states and areas that do
not observe DST on the day before enactment). H.R. 1601 and H.R. 2389 would provide
additional flexibility in DST observance by adding an option for year-long DST observance. S.
4582 would temporarily extend the DST observance period that began on March 8, 2020, through
November 7, 2021.
Information on the benefits and costs of changing the length of DST observance may be of
congressional interest. On March 12, 2018, the House Committee on Energy and Commerce sent
a letter to the DOT requesting updated information related to DST and standard time “to more
fully appreciate the various policy factors associated with changing between Standard and
[DST].”69 DOT responded to the committee with a letter on June 20, 2018, stating the Department

66 European Parliament and the Council of the European Union, Directive 2000/84/EC of the European Parliament and
of the Council of 19 January 2001 on summer-time arrangements.
67 European Parliament, “Parliament Backs Proposal to End Switch Between Summer and Winter Time in 2021,” press
release, March 26, 2019, http://www.europarl.europa.eu/news/en/press-room/20190321IPR32107/parliament-backs-
proposal-to-end-switch-between-summer-and-winter-time-in-2021.
68 European Parliament Legislative Observatory, “Text Adopted by Parliament, 1st Reading/Single Reading,” March
26, 2019, https://oeil.secure.europarl.europa.eu/oeil/popups/summary.do?id=1579670&t=e&l=en.
69 Letter from Representative Greg Walden, Chairman of the House Committee on Energy and Commerce, to the
Honorable Elaine Chao, Secretary of the U.S. Department of Transportation, March 12, 2018, https://republicans-
energycommerce.house.gov/wp-content/uploads/2018/03/031218-DOT-Daylight-Saving-Time-Input.pdf.
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Daylight Saving Time (DST)

has “initiated a literature review of this issue” and it “will share the results” once completed.70 As
of September 2020, the committee has not received the results of the literature review.

Author Information

Corrie E. Clark
Lynn J. Cunningham
Analyst in Energy Policy
Senior Research Librarian

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
shared staff to congressional committees and Members of Congress. It operates solely at the behest of and
under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not
subject to copyright protection in the United States. Any CRS Report may be reproduced and distributed in
its entirety without permission from CRS. However, as a CRS Report may include copyrighted images or
material from a third party, you may need to obtain the permission of the copyright holder if you wish to
copy or otherwise use copyrighted material.

70 Letter from The Honorable Elaine Chao, Secretary of the U.S. Department of Transportation, to Representative Greg
Walden, Chairmen of the House Committee on Energy and Commerce, June 20, 2018, https://republicans-
energycommerce.house.gov/wp-content/uploads/2018/11/07.05.18-DOT-Daylight-Savings.pdf.
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