Atkinson is an English-language surname. The name is derived from a patronymic form of the Middle English Atkin.
These are much more conservative than state laws, in general (for instance, everyone should be in a booster seat from about age 4 to at least age 8) but remain less conservative than some of the european standards (for instance, the European Child Safety Alliance recommends that children remain in rear-facing carseats until 3 years of age).
Children should be in an appropriate safety seat until the vehicle seatbelt fits them correctly, generally when they are about 8-12 years old and 4'9. After that, they should be properly seated with a lap and shoulder belt. Children 12 and under should remain in the rear seat.