Laws vary quite a bit depending on state... I think the most strict is Wisconsin where they have to be 8 years old and weight at least 80lbs and be at least 57 inches tall before they can ride without a booster seat...
Frankly I would probalby be more concerend with the height than the age or weight. Where the shoulder strap makes contact with the child will have more bearing on how safe it is.... I can still remember an old drivers ed film where the shoulder strap lopped the head off a crash test dummy.
Frankly I would probalby be more concerend with the height than the age or weight. Where the shoulder strap makes contact with the child will have more bearing on how safe it is.... I can still remember an old drivers ed film where the shoulder strap lopped the head off a crash test dummy.