Every US state requires children to ride in a car seat or booster seat. The exact age, height and weight rules differ by state; see In your state. The steps below follow the federal safety agency NHTSA.
Even the drive home from the hospital, or from the airport, needs a car seat. Taxis and rideshares often do not provide one. Bring your own, or book a ride type with a child seat where the app offers it.
Rear-facing car seat (babies and toddlers): the child faces the back of the car. Keep your child rear-facing as long as possible, until they reach the top height or weight limit of the seat.
Forward-facing car seat with a harness: after outgrowing rear-facing. Use it until the top limit of the seat.
Booster seat: lifts the child so the adult seat belt fits. Use it until the belt fits correctly.
Seat belt: the belt fits when the lap belt lies low across the upper thighs (not the stomach) and the shoulder belt crosses the chest and shoulder (not the neck). This often happens between ages 8 and 12.
Children under 13 should always ride in the back seat. Never put a rear-facing seat in front of an active airbag.
All seats sold in the US must meet federal safety standards.
Seats from other countries may not meet US rules. Buy one here.
Be careful with used seats: the seat must not have been in a crash, must have its labels, and must not be past its expiration date (printed on the seat).
Register the seat with the maker so you get recall notices.
Many car seats are installed wrong. Certified child passenger safety technicians check your installation, often for free, at fire stations, hospitals and other places. NHTSA's website has a search for car seat inspection stations by ZIP code.
Straps too loose. You should not be able to pinch extra strap at the shoulder.
Chest clip too low. It goes at armpit level.
Heavy winter coats under the harness. Put the coat on backwards over the straps instead.
Moving to the next stage too early.