What is required for passengers under the age of 4 in Pennsylvania?

In Pennsylvania, passengers under the age of 4 are required to be secured in a child safety seat. This regulation is based on the understanding that young children are particularly vulnerable in the event of a car accident, and using an appropriate child seat greatly enhances their safety. Child safety seats are specifically designed to provide optimal protection by supporting a child's head, neck, and spine, which is essential given their developing bodies.

While seat belts are important for older children and adults, they are not sufficient for younger children who need the additional support and restraint that a child safety seat provides. Adult supervision is helpful but does not fulfill the specific legal requirement in place for this age group. Booster seats are typically used for children who have outgrown their child safety seats but are still too small to safely use regular seat belts. Therefore, for those under 4 years old, the correct requirement is indeed the use of child safety seats.