IStock Photo 11253974 © Sean Boggs

There are times when parents lie in bed at night and calculate the odds. Prom night is one of those times.

There is that pesky worry about teenage sex—and parental concern is always heightened when high school boys who have showered, shaved, and outfitted themselves in evening attire show up to escort high school girls who have spent even more time and money making sure they are at their most alluring.

But worries that there might be fooling around in the backseat are trumped by fears about what could happen when the car’s in motion. As midnight rolls towards the middle of the night, mothers and fathers are left to imagine empty beer bottles, car wrecks, and ambulances speeding towards the ER—scenes which are far less pretty than the pre-prom snapshots of just a few hours before.

And according to teens themselves, parents are right to fret.

A 2010 Liberty Mutual/Students Against Drunk Driving survey found 1 in 1.11 11th and 12th graders (90%) thought their friends were more likely to drive drunk on prom night. That’s scary stuff, especially since the odds are already 1 in 8.7 that an junior in high school will drive drunk in a month—and those odds jump to 1 in 5.46 for seniors. And despite public information campaigns and parental pleas and warnings, the odds an 11th grade student will get in the car with a driver who has been drinking are 1 in 3.42, increasing to 1 in 3.17 for 12th graders.

The National Highway Transportation Safety Administration reports that more teens die in car crashes than of any other cause. Although young driver fatalities have dropped since their peak in 2002, according to the CDC emergency rooms treated more than 350,000 teens aged 15 - 19 for crash injuries—in 2008 alone.

Many schools are trying to do their part to try and minimize the risk to young drivers on prom night, encouraging the use of limos, and in this tight economy, even school buses and town trolleys. Pearl River High School, in the New York suburbs, has moved its proms to weeknights—and is enforcing on-time school attendance the following day—in an effort to discourage students from excessive prom partying. Last year 50 of their students were cited for underage drinking, and the school is determined not to have a repeat.

It doesn’t help jittery parents that movie makers and TV producers love turning this classic American rite of passage into a spectacle of horror. From Prom Night (the original and the remake) to Zombie Prom, and from Carrie to Buffy the Vampire Slayer, proms on screen represent the dangers of adolescence writ large. But buckets of blood, hellhounds, and sadistic killers still don’t equal the very real danger of a six pack and a speeding automobile. All parents want to hear is the front door open and the words, “I had a great time.”