A majority of state governments - 33 plus the District of Columbia - has recognized the particular danger that such pressure can pose for young drivers. They limit to one the number of teenagers who may be in a car as passengers with a junior driver, unless an adult also is present. Pennsylvania allows one passenger for each seat belt.

Nationally from 1995 through 2004, drivers between 15 and 17 were involved in 26,453 fatal crashes that killed 30,917 people, according to the AAA Federation. Of those victims, 11,177 were the drivers and another 6,892 were their teenaged passengers. In Pennsylvania over that period, 390 teenaged drivers died in crashes and another 352 teen passengers of teen drivers died in accidents.

In 1999, Pennsylvania adopted a three-tiered licensing system for junior drivers in order to improve safety among new drivers. The results have been dramatic. In 2004, there were 2,800 fewer crashes and 38 fewer deaths among 16-year-old drivers than in 1999, according to Pennsylvania Department of Transportation.

That success mirrors the national experience. A 2005 study by economics professor Thomas Dee of Swarthmore University found a 5.6 percent decline in deaths among junior drivers in the states that had adopted some level of junior license restrictions. He projected that the decline would be 19 percent if all states adopted the highest level of restrictions, as recommended by the Insurance Institute for Highway Safety.

One of those is to reduce the number of teen passengers of teen drivers. According to the AAA, California did so in 1998 and teen passenger deaths declined by 25 percent over three years.

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