ATLANTA — Fatal car crashes involving teen drivers fell by about a third over five years, according to a new federal report that partly credits the drop to tougher state limits on younger drivers.

The number of deaths tied to these accidents fell dramatically from about 2,200 in 2004 to 1,400 in 2008, said the Centers for Disease Control and Prevention report.

The CDC looked at fatal accidents with drivers who were 16 or 17. There were more than 9,600 such incidents during the five-year span and more than 11,000 people died in the crashes.

The rate of these fatal crashes has been declining since 1996. CDC officials credit a range of factors, including safer cars with airbags and highway improvements.

But experts say a chief reason is that most states have been getting tougher, curbing when teens can drive and when they can carry passengers.