Vehicle crashes are the leading cause of death for teenagers in the United States. That’s why states no longer grant unrestricted driver’s licenses to teens once they turn 16, as they did when I was a kid. Instead, states grant driving privileges to teenagers under 18 only after they have been driving under a permit with supervision for a lengthy period of time, and, even then, only by degrees. Driver’s licenses issued to such teens typically restrict nighttime driving and/or the number of minors who may be present in the vehicle for some period of time after initial licensure. While many people readily accept the notion that teens are safer during the graduated licensing period–either because they aren’t driving unsupervised at night, because they don’t have a gaggle of friends in the car, or because they aren’t driving at all given the hassle associated with becoming licensed–they wonder whether the effects vanish once the teens are on their own.