Traffic on the I-495 is backed up from Bethesda to College Park. (Linda Davidson/The Washington Post.)

Nobody wants to hear this, but holiday travel, combined with holiday drinking, will result in hundreds of deaths and injuries this holiday season.

Over the four-day Thanksgiving weekend alone, the National Safety Council estimates 433 deaths and 52,300 injuries requiring medical attention may occur because of car crashes. But the annual projection isn’t meant to scare you off, the nonprofit group says.

“Our goal for providing these estimates is so people can think about the steps they can make to be safe– always buckling up, not speeding, never drinking and driving and not being on their cell phones — to help them be safe on the way to that family get together,” said Kenneth P. Kolosh, manager of the council’s statistics department.

As many as 42 million Americans– including more than a million from the Washington region– are expected to hit the road next week to celebrate Thanksgiving.

Advocates and law enforcement officials are urging safe driving practices, including the use of seat belts, which can save lives during one of the busiest travel seasons of the year. A recent report suggests that car fatalities are on the rise this year, and alcohol and speeding have been top contributors.

Motor vehicle fatalities are particularly high around holidays, with New Year’s topping the list of the deadliest. Thanksgiving doesn’t see a huge increase in motor vehicle deaths, and experts say that is likely because there isn’t a substantial increase in alcohol-impaired driving crashes compared to other holidays.

On average, about 30 percent of all road deaths involve at least one impaired driver, data suggests. But on holidays that share tends to be higher. While the share of alcohol-involved road fatalities on Thanksgiving is about 33 percent, Kolosh said, the number rises to 40 percent on 4th of July and to 44 percent on New Year’s.

“Each Thanksgiving, we begin another holiday season while remembering all we are grateful for,” said Deborah A.P. Hersman, the council’s president and former chairman of the National Transportation Safety Board. “But do not let the frenetic pace of the season rush you on the roads. Be alert and drive defensively so you can celebrate at home, not sit in the emergency room.”

Besides not driving while intoxicated, advocates also urge drivers to avoid driving while tired and encourage parents to not allow their teens to drive around with their peers.  The council estimates that the use of seat belts, which have proven to prevent fatalities, could save an estimated 164 lives during the Thanksgiving holiday period.

About 87 percent of people are said to use seat belts, leaving the remaining 13 percent at greater risk of dying in the event of a crash.