Pennsylvania state law requires that children under age 4 ride in a federally approved car seat that is appropriate for the child's age, height and weight. Children ages 4 to 8 must use a booster seat if they are no longer in a car seat. Pennsylvania law further requires that children ages 8 to 18 use a seatbelt whenever they are in a vehicle, regardless of seating position.
The law in Pennsylvania requires you to properly use the car seat your child uses.

The fine for not using a car seat for a child who should be in one by law is $75.