this Iowa law is pretty standard in any state. ( I had this issue once, involving a big truck going cross country)
As a parent, you may want to consider outfitting all able seats in a motorhome, big truck, or old car, with proper safety belts for kids, or make sure your child gets the front passenger seat with booster. but it is not legally required, and no laws are broken by NOT doing so.
As a parent, you may want to consider outfitting all able seats in a motorhome, big truck, or old car, with proper safety belts for kids, or make sure your child gets the front passenger seat with booster. but it is not legally required, and no laws are broken by NOT doing so.