In Minnesota, all babies under one year old, and all babies under 20 lbs in weight, must ride in a rear-facing infant or convertible car seat, in the back seat of the car.
After a baby's first birthday, and when the baby weighs more than 20 lbs, they must ride in a car seat or booster until their eighth birthday, or are 4'9" or taller.
The law is the minimum standard for child safety. The American Academy of Pediatrics provides car seat safety recommendations to improve the safety of babies and children in cars.
The AAP recommends that babies and toddlers ride rear-facing in a suitable seat for as long as possible, until the child reaches the upper height or weight limit for the seat.
Then, they recommend that toddlers and preschoolers ride in a car seat with a five-point harness as long as possible.
Once a child has outgrown their child seat, the AAP recommends that they ride in a booster seat until they are big enough for adult seat belts to fit them properly. The AAP recommends booster seats for all children under 4'9" and that booster seats be used until the child is somewhere between 8 and 12 years of age.