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  • Writer's picturePatrick Durkin

Year-Round Daylight Saving Time Reduces Deer Crashes

   When the humorist Dave Barry turned 50 in 1998, he compiled a list of things that took him a half-century to learn.

   One of his insights never fails. Ever: “A person who is nice to you but rude to the waiter is not a nice person.”

   Barry was also right about this: “You’ll never find anybody who can give a clear and compelling reason why we observe daylight saving time.”

   Nor can many of us remember daylight saving time is when we turn clocks forward an hour in spring, and that standard time is when we turn clocks back an hour in fall.

   It’s not as though we haven’t given DST a fair trial. According to Wikipedia, the first nationwide mandate to spring forward one hour was issued by the German and Austro-Hungarian empires on April 30, 1916. The United States followed in 1918 during World War I to conserve energy and add daylight to the workday.

   The U.S. also imposed DST year-round during World War II, and again in 1974 during an energy crisis. I recall folks hating that ’74 mandate, given that workers and school kids tediously debated if we truly saved energy by waiting in pre-dawn darkness for the bus.

   But we liked assuming Ben Franklin invented the idea in 1784 while working in Paris. Only later did we learn Franklin simply noted Parisians would burn less oil and fewer candles if they just woke up earlier in summer. To help make everyone healthier, wealthier and wise, Franklin joked in a newspaper letter that Paris should ration candles, tax window shutters, and fire cannons and ring church bells each dawn.

   Franklin couldn’t have known of another practical reason for year-round daylight saving time: It reduces deer-vehicle collisions, thereby saving lives and reducing insurance premiums. Safe to say, deer-buggy collisions weren’t much trouble anywhere in 1784.

   In contrast, deer-vehicle collisions have plagued the U.S. for about 50 years. We pause to note that this plague comes with annoying conspiracy theories about insurance companies paying off wildlife agencies to reduce deer numbers. That’s nonsense, given that the risk factors of deer-vehicle crashes are easily calculated by actuaries who help set premiums so insurers seldom lose money.

   Now, about deer-vehicle collisions and daylight saving time: University of Washington researchers, led by Calum X. Cunningham and Professor Laura Prugh, show that standard time leads to far more deer-vehicle collisions than does DST ( And it’s not because of any behavioral changes in deer. It’s all about time changes that put more people on dark roads when deer are most active and less visible.

   Cunningham noted that deer-vehicle collisions are tightly clustered in the hours before sunrise and after sunset in all states, with 76% of crashes occurring at night. The collisions’ timing closely tracked seasonal and latitudinal changes in daylight, while the timing of vehicle traffic shows no substantial change during the year, indicating that clock time, not solar time, is the major factor in traffic volume.

   By reviewing over 1 million deer-vehicle collisions in 23 states from 1994 to 2021, the researchers found those crashes are 14 times more likely in the two hours after sunset than in the two hours before sunset. While deer activity is roughly the same at dawn and dusk, traffic volumes increase in the evening while visibility worsens. Therefore, deer-vehicle collisions increase with standard time’s hour-earlier sunsets, including a 16% increase in the week after autumn’s clock rollback.


   The study found if we used DST year-round, the U.S. would save $1.2 billion annually in deer-vehicle collisions. The researchers further estimated year-round DST would prevent 36,550 deer-vehicle collisions annually, while year-round standard time would add 73,660 crashes, a difference of over 110,000. Their estimates also show year-round standard time would bring 100 more deaths, 6,000 more injuries, and at least $3.5 billion in annual costs.

   Cunningham’s team also found significant differences in deer-vehicle collisions based on location. Counties in the nation’s northern latitudes, where winter day lengths are shorter, averaged 1.86 times more collisions than counties in more southern latitudes. Likewise, counties in eastern portions of a time zone, where the sun sets earlier than in the west, averaged 1.35 times more collisions than counties along the same time zone’s western border.

   In fact, the researchers think even far northern areas like Alaska, which experiences more extremes in day length than do states in the Lower 48, might see fewer deer-vehicle collisions with year-round DST.

   All those savings further increase when looking beyond deer-vehicle collisions. Year-round DST would prevent 366 fatal pedestrian-vehicle accidents annually by adding about 20 weeks of brighter daylight in the late afternoon/evening hours. In contrast, adding 32 weeks of standard time would cause 610 fatal pedestrian-vehicle accidents, for a 1,000-fatalities difference.

   And yet … the researchers note people typically disliked earlier efforts at year-round DST, noting many nations tried it from 1918 to 1919 and 1942 to 1945; and tried again from 1974 to 1975 in the United States; 2011 to 2014 in Russia; and 1968 to 1972 in the United Kingdom. The results? Those governments backed off every time, enduring the annoying time changes each spring and fall rather than trusting folks to adjust once and get over it.

   In fact, in a recent New York Times editorial (, Professor Prugh noted that over half of Americans want to “ditch the switch” between standard and saving times each fall and spring, with most preferring year-round standard time by margins of 10 to 20 points.

   Meanwhile, the U.S. Senate passed the Sunshine Protection Act two years ago to impose DST year-round nationwide, but the bill died in the House. Prugh worries that impasse will frustrate individual states, causing them to impose standard time year-round without realizing its real-world costs to society.

   One can surely doubt whether most voters will be intrigued by the savings revealed in research on deer-vehicle collisions. And we can probably expect even less from our U.S. House of Representatives, given the necessity of grasping facts and data. As Mark Twain wrote: “Reader, suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself.”

   But making daylight saving time permanent would show bipartisan common sense that would save lives and end a longtime national annoyance.

Deer activity is similar at dawn and dusk, but autumn’s nationwide shift to standard time puts more vehicles on the road at dusk and early darkness when it’s harder for drivers to see deer crossing roads. Patrick Durkin photo

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