Teens across Michigan are celebrating the end of the school year, high school graduations and the carefree summer months. But the Michigan Teen Safe Driving Coalition warns parents not to stop monitoring their teens' driving habits. Memorial Day marks the start of a period commonly known as the 100 deadliest days on the roads for teens. Between Memorial Day and Labor Day in 2012, 33 people were killed in Michigan in crashes involving teen drivers, according to National Safety Council estimates based on data from the National Highway Traffic Safety Administration. More than 1,000 people nationwide were killed in teen-related crashes during the same period. Car crashes are the leading cause of death for teens in the U.S.