July 4 Travel on U.S. Roads Can Be Deadly

7-3-17 July 4th traffic
Traffic makes its way along Interstate 80 on July 1, 2015, in Berkeley, California. The Fourth of July holiday period is a dangerous time to be on the road in the U.S., according to the National Safety Council as well as a study by Geotab. Justin Sullivan/Getty Images

The Fourth of July marks the anniversary of the day the Continental Congress adopted the Declaration of Independence in 1776, announcing that the colonies were claiming independence from British rule. The anniversary, almost two and a half centuries later, is full of barbecues, fireworks, trips and other celebrations.

But the holiday weekend period also is a dangerous time to be on the road, getting to and from all of these festivities. The National Safety Council (NSC) estimates that about 582 people will die in car crashes during the holiday period, from 6 p.m. on Friday evening through 11:59 p.m. on Tuesday. The NSC, a nonprofit organization that works to eliminate preventable deaths on the road and elsewhere, also anticipates that 66,900 others will be seriously injured in crashes during the same period, requiring medical attention.

"The council issues these estimates to empower drivers to make safe decisions behind the wheel, because the only acceptable number of deaths is zero," Deborah A.P. Hersman, president and CEO of the NSC, said in a statement. "We hope Americans will spend their holiday safely watching fireworks and celebrating with families rather than sitting in an emergency room."

Since July 4 falls on a different day each year and the "holiday period" isn't always the same length, the NSC estimated the fatalities and injuries during this year's 4.25-day stretch using equivalent periods in previous years—in 1995, 1996, 2000, 2002, 2006 and 2013. The NSC found that similar holiday periods result, on average, in 613 crash fatalities out of 3,850 in July, or roughly 15.88 percent of the month's deaths. Similar-length periods around weekends before and after the holiday resulted in an average of 524 deaths. The organization also predicted the number of deaths for July 2017 using a forecasting model and, combined with the calculated percentage, estimated that nearly 600 people will die in car crashes by Tuesday night.

A separate study by Geotab, a telematics and GPS vehicle tracking company, found that July 4 is the deadliest day to drive in the U.S. The study calculated a "fatal crash rate" representing the number of fatal crashes per one billion vehicle miles traveled by taking the number of fatal crashes between 2006 and 2015 (from the National Highway Traffic Safety Administration's Fatality Analysis Reporting System) and weighing it against vehicle miles traveled (from Federal Highway Administration's Traffic Volume Trends). It also calculated the deadliest day on the road by state. In Nevada, New Mexico and Minnesota, July 4 had the highest fatal crash rate.

7-3-17 July 4th traffic

Click the image to open the full interactive version (via Geotab).

Though Geotab and the NSC both indicate that July 4 or the holiday period surrounding it are deadly, they don't necessarily agree on the explanation. The Geotab study "may be mathematically accurate, but I don't think it helps inform the public about what risk they face this year," says Ken Kolosh, manager of statistics at the NSC, who questions the methodology.

For one, he says, the federal government estimates the miles traveled data on a monthly rather than daily basis. Kolosh guesses that Geotab used a daily average, which reduces the accuracy of the result considering the large daily fluctuations in miles driven. The major issue he sees in the study is that while using multiple years' worth of data can help make such a study more reliable, in this case it's problematic, considering each date falls on a different day of the week each year and the fact that "an individual's risk for being in a fatal crash is always higher on a weekend than on a weekday." Averaging different days of the week together over several years can also skew the results.

"The most dangerous day of the year always sort of varies because of how the calendar falls," Kolosh tells Newsweek. Still, "it's always going to be a holiday or weekend day. It does tend to peak around the summer months, but is generally also high in October, as well," he says. Still, "this Fourth of July is unfortunately going to be a dangerous holiday period."

A spokesman for Geotab says that the company indeed averaged out the monthly traffic volume and used a daily average of miles driven for its study. He adds that "since the data spans more than seven years, each day of the year has fallen on each day of the week, thus cancelling out the day of the week bias."

What's clear is that the holiday period tends to see a higher rate of crash fatalities that involve alcohol impairment. In 2015, the most recent year for which final data are available, roughly 29 percent of fatalities involved at least one alcohol-impaired driver, Kolosh says. But that shot up to 36 percent during the holiday period.

The NSC suggests several measures travelers can take for a safer holiday, including wearing seat belts, putting children in appropriate safety seats, arranging for a designated alcohol- and drug-free driver or alternate transportation, never using a cell phone while driving, making sure the driver is well rested, checking for recalls and not allowing teens to drive with other teens in the car.

Alcohol "plays role in a lot of holiday festivities, which translates into more than the typical number of impaired drivers on road," Kolosh says. Even if a driver is alcohol free, he or she should be aware of the possibility that there's a higher chance than usual of encountering an impaired driver. His advice is to "be very vigilant, follow the speed limit, buckle up."