In a new report, the Governors Highway Safety Association highlights that many passengers in rear seats fail to wear seat belts, despite the role they play in preventing fatalities during car wrecks.

The back seat is often treated as a spot where it’s OK to bend the rules regarding seat belts. And, considering the millions of people expected to be on the road this Thanksgiving week, there’s a good chance that a lot of those people will be filling cars driving down HOV lanes, country roads, and parkways around the country.

The Governors Highway Safety Association (GHSA) has a message for those people: Don’t treat seat belts as an optional feature. Buckle up, no matter which seat you’re sitting in.

The association this week issued a new report, “Unbuckled in Back: An Overlooked Issue in Occupant Protection,” as part of its ongoing series on highway safety issues. The author of the study, Dr. James Hedlund of Highway Safety North, noted that the timing of the study is not coincidental.

“Families traveling together at the holidays often means adults sitting in rear seats, where they may not be accustomed to buckling up in the same way they are when the get in the driver’s seat,” he said in a news release. “It’s important to remind folks that seat belts are there to protect them—in both the front and back seats.”

The report notes a startling statistic from 2013 that brings the point into perspective: Of the 883 unrestrained back-seat passengers who died in car accidents, more than 400 may have survived if they’d been wearing a seat belt.

Seat-belt use in back seats raises serious issues for a few reasons. For one, just 78 percent of passengers say they wear a seat belt when sitting in the rear, compared with 87 percent who use belts in the front seat. For another, failure to wear a seat belt in a rear seat is not treated as a primary offense in 32 states—which means that cars generally won’t get pulled over simply because a rear passenger isn’t buckled in. And, with the increase in passengers using ride-sharing services such as Uber and Lyft, it’s becoming common for adult riders to sit in the back seat.

The association notes that there have been two high-profile accidents just this year involving passengers riding in the back seat of a hired vehicle: an accident in February killed CBS reporter Bob Simon and an incident in May that killed famed mathematician John Nash and his wife, Alicia. (Nash’s life story was portrayed in the Oscar-winning film A Beautiful Mind.)

GHSA’s executive director, Jonathan Adkins, noted that the two incidents sparked the group’s interest in studying the issue.

“Convincing adults to buckle up, every trip, in every seat will require a concerted effort among lawmakers and highway safety professionals, but the lives saved will be well worth it,” he said.

The full study is available on the GHSA website.